28 across: Increase tenfold the gist of legal restriction (5)

This is super nasty but brilliant, and a thank you to AL once more for deciphering the clue.  And it goes: legal = licit, gist of legal = c, increase tenfold the gist of legal = limit (10 x 100 (c) = 1000 (m)) = restriction.

17 across: Nerd censored shot (6, 3)

Quality: nerd = square and censored = cut so that nerd censored = square cut = shot.

13 down: Weighlifter fights pirate? (4, 7)

Very nice: weightlifter = jack and fights = spar + row so that weightlifter fights = jack sparrow = pirate.

23 down: Pontoon, perhaps, reaches sailor on Persian Gulf (5)

Awesome clue, whose explanation I must thank JD for, and it’s even got a q in it that is used in a cross clue. Pontoon, perhaps = qa (pontoon is a variation of blackjack or 21, and a queen and ace (qa) give pontoon, blackjack or 21) and sailor = tar, which gives pontoon, perhaps, reaches sailor = qatar = on Persian Gulf.

16 down: Expedient milk drink peeved Spooner (9)

Are Spooner clues a DA original? Do they exist anywhere else? Anyway, I love them, and I loved this one: milk drink = shake and peeved = miffed so that milk drink peeved Spooner = makeshift = expedient.

14 down: Guards causing endless ruckus about … revolt (10)

Hat-tip to Michael Fuller for the explanation of this cute clue: causing endless = causin and … = dots so that causing endless ruckus about … revolt = custodians = guards.