Fifteensquared

Prize puzzle from the Weekend FT of October 24
Don’t you love 4D? How about 21 and 24D? Thank you, Cincinnus.

Across
1. DABCHICK – BAD backwards + CHICK (young one)
5. WALLOP – double definition. Wallop is a slang term for beer.
9. GIN RUMMY – GIN and RUM (drinks) + M[a]Y
10. UPROAR – PROA (boat) in UR (old city)
12. APHID – A (a) + P[arty] + HID (kept under wraps)
13. REPELLENT – ELL (measure) in REPENT (feel remorse)
14. VARIES – V (V) + ARIES (sign)
16. STOLLEN – TOLL (tax) in SEN (senator)
19. HOKUSAI – OK (fine) + USA (country) in HI (greeting)
21. PLAINT – I (one) in PLANT (factory)
23. COLUMBINE – L (Lake) + U (Superior) in COMBINE (join forces)
25. TARSI – TARS (old sea dogs) + I (island)
26. LIMPID – LIMP (lacking firmness) + ID (I had)
27. STEP ON IT – anagram of NEPOTIST
28. STRICT – [di]STRICT
29. INDECENT – C[astl]E in INDENT (order)

Down
1. DOG-EAR – anagram of GO RED A[ce]
2. BENCHMARK – BENCH (magistrates) + MARK (note)
3. HOUND – H (hot) + anagram of UNDO
4. CAMERAS – anagram of CREAM + AS
6. APPALOOSA – APPAL (shock) + OO (repeated exclamation) + AS (while) backwards
7. LOOSE – double definition
8. PIRATING – PI (sanctimonious) + RATING (sailor)
11. APIS – A (a) + P[haroah] + IS (is)
15. INSOMNIAC – anagram of MONICAS IN
17. LONG RANGE – LON[don] (capital, don abandoned) + GRANGE (country house)
18. CHUCKLES – CHUCK (one chap) + LES (another chap)
20. IRIS – I (one) + R[upert] + IS (is)
21. PRESTON – PRESTO (quickly) + N (name)
22. DIKTAT – KID (child) backwards + TAT (shoddy articles)
24. LEMUR – L (large) + EMU (bird) + R (runs)
25. TEPEE – initial letters