14 down: K-kinky assumption lessened (9)
You just don’t expect one letter is gonna be the direct definition: kinky assumption lessened = potassiumn lessened = potassium = K.
15, 16 across: Daughter suggests London custom (8, 2, 3, 5)
The pick of the bunch, and another excellent example of the answer being the wordplay: daughter = changing of the guard (the guard is an anagram of daughter) = London custom.
11 across: – cryptic clue? (9)
Very nice indeed, and almost &lit: – cryptic clue = minus cule = minuscule = – cryptic clue.
12 down: Timeless African people climbing of mountains intact? (10)
Nice: timeless African people climbing of mountains = timeless Bantu climbing ridged = timeless utnab ridged = unabridged = intact.
8 down, 13 across: Briefly make 2-down (saga) droop? (3, 1, 4, 5, 5)
Nice double definition: make saga droop = cut a long story short = briefly.
Update: NC set me straight in the comments: this is a much cleverer clue than I was giving it credit for, and is another brilliant example of the answer being the wordplay: make saga droop = make saga sag = cut a long story short = briefly.
21 across, 1 down: Hollywood creep to defect, seizing Israeli plane abroad to central China (4, 6)
I loved the direct clue: defect, seizing Israeli plane abroad to central China = bug seizing el al os i = Bela Lugosi = Hollywood creep.
4 down: Romcom’s Richard accepts new romcom, for one (5)
Brilliant: DA got a star of romantic comedy into the answer concerning romantic comedies: romcom’s Richard accepts new = Gere accepts n = genre = romcom, for one.