1. Fancy brief hot pants, arty, tight PHANTASTRY (anag. incl. H) Not a great deal of rearrangement of the letters required, but the solver needs to take a guess at which of ‘fancy’ and ‘tight’ is the definition and which the anagram indicator.
18. Clan leader following son as anti-establishment type SKINHEAD (s + kin head) The definition comes from Chambers ‘a young person with closely cropped hair, … displaying aggressive anti-establishment behaviour’.
19. Monetary unit, risen in rank, king struck RUPEE (up in ree(K)) Dr Watson couldn’t find enough evidence that ‘rank’ and ‘reek’ are the same part of speech, though this appears to be the intention of the wordplay. Update – It’s been pointed out elsewhere that the intended wordplay is probably ‘ree(king)’.
20. Tiny element of genetic change, one of pair removed from sheep MUTON (m(o)uton) One of the pair of o’s in ‘mouton’ must be removed.
24. Ray maybe doffing cap, one of pair flanking doorway ANTA ((m)anta) Solvers looking for a well-known person called Ray will search in vain.
29. Dye, fashionable, worked out, I extend for lining INDIGOID (in + I go in did) There are a few uncommon synonyms to piece together in this clue.
30. Star swallows cocktail – it’s gone down fast! SKI RUN (kir in sun) One of Azed’s trademark punning definitions.
3. First of wines included in bill, that is e.g. Beaujolais Nouveau NEWBIE (w in neb + i.e.) ‘Newbie’ might not be a word you’d naturally associate with the wine trade, but Azed picks up on the Chambers definition ‘a new arrival’.
6. A racket I’ll yield to in sound commercial practice TRADING (a din for I in trig) The key to the clue is finding trig2, meaning ‘sound’ in the same sense it’s used in the surface reading.
7. Royal cubit used in measurements REMEN (hidden) The neat wordplay looked familiar, and a quick search revealed that Dr Watson’s very first review for Azed 1502 in 2001 included praise for the even briefer ‘A unit of measurement’, also at 7 down. In his comments on the puzzle, Azed noted the clue was “one of those ‘it-has-to-be’ windfalls that very occasionally fall into one’s lap and one that may perhaps have been used before, though I don’t recall seeing it.”
10. Gas valve? Bell-end pipe needs adjusting BLEED-NIPPLE (anag.) Somehow the setter manages to steer clear of all the potential double entendre in both clue and solution.
21. Hauls in warps? Not I, free from such? UNLASH (anag. less I) Very much a semi-& lit. clue with the definition referring back to ‘warps’, meaning a type of rope or thread, in the wordplay.
26. Linked compilation, as present in court SEGUE (e.g. in sue) ‘As’ is a slightly unusual indicator for ‘e.g.’, but it may be used to mean ‘such as’.
Across: 11. HAVEREL (have + rel(y)); 12. RETAIL (I in later, rev.); 14. DIAMANTE (a man in dite); 15. TURBOT (b(one) in anag.); 16. ECHE (hidden); 17. POIS (2 mngs.); 22. EVENSONG (ven(I)son in e.g.); 25. SIRI (iris, rev.; pan3); 27. ASLEEP; 31. DEISEAL (E in anag.); 21. MESENCHYME (M + anag.).
Down: 1. PHOTORESIST (hot in pores + anag.); 2. HAPU (ha’ + up, rev.); 4. TRIOSE (I in anag.); 5. SLICKENSIDE (kens id in slice; ken2); 8. DANCETTES (dance + anag.); 9. LITH (lit + H; lit = drunk); 13. PROPERDIN (proper din); 18. STOLONS (hidden); 20. MASTIC (Asti in MC); 26. INKY ((K)inky); 28. EXAM (hidden).