1. Pay is adjusted with mostly modest woman involved in mental affliction. PSYCHASTHENIA (chast(e), hen, all in anag.) Some word listed under psycho- was the best bet here for a quick early start.
11. Driver best given a wide birth, for whom it’s a game injecting heroin. JEHU (H in jeu) The ‘given’ was printed in Watson’s copy as ‘give’, an obvious typo. Our road hog was Jehu, famed as a fierce charioteer.
12. A Queensland native, it could be said. SIDA (anag.) A clue seeming to be a homophone. Watson was bamboozled for quite a while - too much cider, perhaps.
14. A country using French currency is making good. UNPAYS (i.e. un pays) ‘French currency’ may be understood as meaning ‘current French’.
26. Ancient ox, last to munch oil secreted in juice of poison ivy. URUSHIOL (urus, h, anag.) ‘Secreted’, used to indicate the anagram (of ‘oil’), may have troubled one or two solvers until finding the listed meaning (of ‘secrete’): ‘to form and emit ... ’. That may be understood here as meaning to press out.
29. Of bone. OSTEAL (o’, steal, & lit.) Not the Competition word, but a fine & lit. clue. None of it is superfluous to either the definition or the cryptic indication.
30. Former interval Ben’s shrugged off, sickly. TWEE ((be)twee(n)) The entry for ‘between’ as noun includes ‘an interval (Shakesp)’. Our Ben may be taken most aptly as a reference to Ben Jonson.
2. Antelope, one found in part of NZ. SUNI (un (or ’un) in SI) The reference to ‘un’ (as meaning one) is not to the French, but to the English dialect word (q.v.). The suni is usually found in South East Africa, but perhaps also in a South Island zoo.
4. Mills maybe mostly producing sound for poet of yore. HAYLE (i.e. Hayle(y)) Our solution is (with DISTENT) the first of two words sourced to the poet Edmund Spenser. The other reference here is, of course, to Hayley Mills.
5. The USA’s one reverberates with ultimate in eloquence? SENATE HOUSE (anag. inc. e) The spine of the puzzle, quickly found by Watson and many others, he suspects. Add &lit according to taste.
6. Force? It briefly worsened … THRUST (’t, anag. (of HURTS)) The first of a linked (with 7) pair of clues indicated by the triple dots (ellipsis). This is an example of the rarer kind where the solution of one is referenced in the cryptic part of the other. More common is the pairing where the surfaces of two consecutive clues are improved by being read together. Watson cannot avoid noting that, in the present clue, the anagram part is rendered indirect, normally considered to be unfair to the solver. However, the letters required here are indicated by a full cryptic clue, as follows ...
7. … Such wounds − unit required by the sound of it. HURTS (‘Hertz’) The other clue of the pairing, a simple homophone, providing the letters for the anagram in the first, as discussed above.
21. Brief letter, one from Greece that’s yellow on fading. PHILEM (phi lem(on) & lit.) The fragment of St Paul’s letter to Philemon depicted here is not exactly lemon yellow, but we know what Azed is getting at. The full text of the letter in the King James Bible may be read here, and more extensive discussion of its meaning here.
22. Rule in e.g. French described. DRAWN (r in Dawn) An obvious and rather overdone reference (in crosswords generally) to Dawn French.
23. Gently (G) − who’s playing that period instrument? SHAWM (i.e. Shaw, M.) Dr Watson is not a fan of detective programmes and took a while to find the explanation here. The references are to Martin Shaw and Inspector George Gently ...
27. E.g. Christian wretchedness, as of old. BALE (ref. C. Bale) ... and here, apparently, to one Christian Bale.
Across: 10. BULLA (bull5, a); 17. SAUTERNE (anag. inc. E); 18. DISTENT (hidden, ref Edmund Spenser); 20. OSTEOPETROSIS (anag.); 24. HORNIST (RN in hoist); 28. SADZA (sad, ZA); 31. WEST (The Competition Word); 32. ETTLE ((n)ettle); 33. UNSYMMETRISED (anag.).
Down: 3. CLATTER (anag.); 8. NIGROSINE (gin (rev.), in in rosé); 9. IDENT (den in it); 10. BUNDOBUST (B, undo, bust); 13. AREOSTYLE (anag. in ale); 15. POSTLUDES (lud in anag.); 19. NONETTI (net2 in ‘not I!’); 25. RISER (r, is, re (rev.)).