The Puzzle Section has an extensive list of cryptic shorthands and abbreviations. And, of course, there’s a Wikipedia page with a list of abbreviations as well.
It’s a Wikipedia article, so if there’s something you think is missing, just go in and edit the page.
But more specifically for DA, the following might trip you up:
- Every now and again, one needs to think of a word’s alternative pronunciation to get at the meaning DA is actually referring to. Cases in point:
- flower referring to a river, as in something that flows;
- wicked referring to something with a wick in it, like a candle or a firecracker.
- Little can just be l;
- Often a subject pronoun and a verb will refer to a person. Cases in point:
- She cleaned referring to Sadie, the cleaning lady;
- He animates referring to Matt Groening, the Simpsons animator;
- He turns majestically referring to Muttiah Muralidaran (on this particular occasion, subject pronoun, verb and adverb!)
- In DA’s hands, top can either mean to grab the first letter of the next or previous word, or it can mean to behead the first letter of the next or previous word, i.e. top mark can possibly mean m or ark, as well as A, 10, screamer, Michael Diamond etc.
- Take note of words like nog, not and athena — DA has used those words to mean no g, no t and a then a respectively!
- DA is fond of using mo to mean a second, a moment etc., which it seems a whole lot of people trip themselves up on — even those of us familiar with DA’s penchants.
DA Trippers 
He also likes to refer to himself ie ‘I’ or ‘compiler’ to mean ‘da’.
I think that’s fairly universal.
I’ve also seen one seen one of the Guardian compilers use “Guardian” to mean “we”. Not sure if that would work for a compiler such as DA who is in multiple papers, though in other respects he is not ashamed of his Melbournite bias.
Some more that seem to be unique to DA:
“band”, “bang” and “bank”, indicating removing the d, g, and k respectively.
“Lowering head” indicating moving the first letter to the end. E.g. “Cow lowering head” = OWC.
Specifics
“discover” (dis-cover) can mean remove first letter.
“dock” commonly used to mean remove last letter.
“extremes” can mean first and last letter.
“hands” can mean H and S. In this case spaces have been removed to misdirect the solver.
“bondage,” which commonly means SM, can mean SANDM.
General
Definitions, or defs, are rarely straightforward. Often the answer is an obscure or rarely used sense of the def. E.g. “all humans” = GLOBAL
Clues that consist of anagram, anagram indicator (anagrind) and def, and nothing else, are not very common (once or twice a puzzle). Other setters will throw these bones to solvers in larger numbers (half a dozen or more per puzzle, perhaps?), but DA is too conniving (or sadistic?) for that. Anagrams are more likely to be part of a larger clue.
He also uses a feigned stutter. For example:
“s-stutter” could equal STRIP (S + TRIP as a synonym for stutter)
CONTAINERS
DA likes containers – a word (or part of a word) within another word. DA uses a wide range of words to indicate this mechanism, but the most common containment indicator is ‘in’. Possibly the second most common indicator is ‘during’.
Words are sometimes modified (e.g. first letter removed, or jumbled, or reversed) before being inserted into the other word.
On rare occasions there are nested containers. That is, a word within a word within a word. This can make for some rather convoluted clues.
REVERSALS
On average a few times per puzzle, DA will use a reversal in the wordplay.
‘back”, “up” and “over” appear to be DA’s most common indicators of reversals.
Verbs starting with “re-” are sometimes used to show reversals: “returned”, “reviewed”, “reflected”, “rejected”, etc.
Adjectives/nouns starting with “up-” are also used: “upstanding”, “uplifting”, “uprising”, etc.
Example:
Prepared bait in grass to repel orchard pest
In this clue, the solver needs to find a word meaning grass and reverse it. So TURF > FRUT. (Then place the scrambled letters of “bait” inside FRUT to get the final answer – FRUIT BAT)
In this example, “repel”, or “to repel”, is the reversal indicator.
Sometimes hiddens (another clue type) are reversed. In these cases there will be a hidden indicator and a reversal indicator.
REMOVE FIRST LETTER
Roughly once or twice a puzzle, there is an instruction to remove a word’s first letter.
Here’s an example:
Dance way above ceremony, topless (5)
The answer is STOMP – a kind of dance.
So ‘dance’ is the definition. How about the wordplay?
‘way’, as it often does, gives ST.
Then a word meaning ‘ceremony’ – POMP – is decapitated to provide OMP. Put ST and OMP together to get the answer.
There are a range of remove-first-letter instructions. One of the most common is in the example above – topless.
Other instructions that DA uses include:
top
discover or discovered
heading off
loses/losing/lost + roof/face/lead/head
uncrown, behead, etc
For removing initial H, there is a sub-set of instructions:
(for) Cockney
common
in East London
E.g.
Cockney dope in trial tumult (7)
Answer: TEMPEST
In this example ‘Cockney’ means take the H from HEMP (synonym of ‘dope’) to get EMP. Then place EMP in TEST (synonym of ‘trial’) to get the answer (which is defined by ‘tumult’).
“invoice” = in voice, which indicates a homophone.
“offender” meaning remove the last letter [off – ender].
“offenders” meaning remove more than one of the letters at the end of the word [off – enders].
What does he mean when he writes “Some answers are related and thus go undefined?
Hey Inga, DA means that there is no definition in the clues, i.e. it’s all wordplay, and the definition is related to the theme that you slowly have to piece together.
Why isn’t da working on my iPad today?
I would like to know how to engage with others online who are solving DA, if this is what the site offers?
Is his crossword available without subscribing to the newspaper?
Is there a Meetup group doing DA?
Good questions @Paul T.
Wéve had limited connection with DA et al.
Some of us are trying to arrange a ‘meetup’ group.
NATO Alphabet
DA will use this quite often for single letters eg in last Fridays “whiskey” in 25 across was “w”.