A themed puzzle as usual with one answer I cannot get. Any help appreciated. Thank you Gozo.
Unless you are a specialist in period instruments you will be needing a dictionary for this puzzle!

| ACROSS | ||
| 1 | CYMBAL | Youth leader and doctor in a state (6) | 
| Youth (leading letter of) and MB (doctor) in CAL (California,a state) | ||
| 4 | DULCIMER | Multi-coloured posh tool left out oddly (8) | 
| anagram (oddly) of MULtI-ColouRED missing U (posh) TOOL | ||
| 9 | RACKET | Deafening noise that’s used on court (6) | 
| double definition – forerunner of the Bassoon | ||
| 10 | CLARINET | At home, covered in wine (8) | 
| IN (at home) inside CLARET (wine) | ||
| 12 | MELODICA | Lemon cut and squeezed and acid turned out (8) | 
| anagram (squeezed?) of LEMOn (cut) then anagram (turned out) of ACID | ||
| 13 | ZITHER | Spot woman (6) | 
| ZIT (spot) HER (woman) | ||
| 15 | LUTE | Clay instrument with top missing (4) | 
| fLUTE (instrument) missing top letter | ||
| 16 | OPHICLEIDE | Police hide-out (10) | 
| anagram (out) of POLICE HIDE – an early saxophone | ||
| 19 | FORTEPIANO | Fine operation is off (10) | 
| anagram (is off) of F (fine) and OPERATION | ||
| 20 | OBOE | Not broken evenly (4) | 
| ec=very other letter (evenly) of nOt BrOkEn | ||
| 23 | ATABAL | Attending afternoon dance, learner dropped off (6) | 
| AT (attending) A (afternoon) then BALL (dance) missing L (learner) – an African drum | ||
| 25 | TROMBONE | Time that’s good in French in capital (8) | 
| T (time) with BON (good in French) in ROME (capital) | ||
| 27 | CIMBALOM | Strangely incommutable, but lacking tune (8) | 
| anagram (strangely) of InCOMMutABLe missing TUNE – a type of dulcimer | ||
| 28 | VIELLE | Live broadcast with the French (6) | 
| anagram (broadcast) of LIVE then LE (the, French) – a hurdy-gurdy | ||
| 29 | SIDE DRUM | Homicide one’s rejected (4,4) | 
| something to do with MURDER I’S reversed? | ||
| 30 | TABORS | Thanks to disheartened fighters (6) | 
| TA (thanks) and  | 
||
| DOWN | ||
| 1 | CARAMEL | Irish lass swallows a sweet (7) | 
| CARMEL (Irish girl) contains A | ||
| 2 | MUCH LATER | Camel hurt – treated ages after (4,5) | 
| anagram (treated) of CAMEL HURT | ||
| 3 | AMENDS | Changes what happens at noon (6) | 
| AM ENDS at noon | ||
| 5 | UGLI | Some rail guard brought up fruit (4) | 
| found inside raIL GUard reversed (brought up) | ||
| 6 | CARLISLE | Vehicle left on offshore territory in Cumbria (8) | 
| CAR (vehicle) L (left) on ISLE (offshore territory) | ||
| 7 | MUNCH | Chew a lot, swallowing quarter of the nuts (5) | 
| MUCH (a lot) contains Nuts (one quarter of) | ||
| 8 | RETIREE | Pensioner (sapper) on Hebridean isle (7) | 
| RE (Royal Engineer, sapper) then TIREE (Hebridean isle) | ||
| 11 | SCEPTIC | Non-believer, small commander, holding distressed pet (7) | 
| S (small) CIC (commander) contains anagram (distressed) of PET | ||
| 14 | SIGNORA | Duck inside, a ring’s produced and she’s married (7) | 
| 17 | IMBROGLIO | Explosion in oil rig, with mob in confusion (9) | 
| anagram (explosion in) of OIL RIG with MOB | ||
| 18 | LEGAL AID | Member with a turned up face getting payment for lawyer (5,3) | 
| LEG (member) with DIAL (face) reversed (turned up) | ||
| 19 | FRANCES | Our near neighbour’s girl (7) | 
| FRANCE’S (belong to the UK’s near neighbour) | ||
| 21 | ELEVENS | Apparently singular snack for teams (7) | 
| postulated singular of “elevenses” (snacks) | ||
| 22 | AMRITA | Nectar from Welsh MP and Meter Maid (6) | 
| AM (Assembly Member, Welsh MP) then RITA (lovely Rita meter maid…) | ||
| 24 | AIMED | First-class waters are targeted (5) | 
| AI (A1, first class) then MED (waters) | ||
| 26 | NON-U | Socially unacceptable marriage being over, I quit (3-1) | 
| UNiON (marriage) reversed (being over) missing I | ||
14d signora
16a is ophicleide not ophicleide—thanks for the blog.
Sorry should be not ophecleide!
Thank you Oldham, defeated by my own typos!
I needed both an anagram solver and a dictionary. I usually enjoy a Gozo themed crossword but not this one – too many obscurities for me. I will say that the down clues were, as usual, nice and helpful, it is just that you needed to be an expert in period instruments to get to grips with the acrosses
Thanks to Gozo and PeeDee
All solved apart from the (erroneous?) SIDE DRUM. Looked up SIRE DRUM but 24d soon put paid to that. Lots of unknown instruments made this a bit of a grind but, who knows, some of them may stick and be useful in the future.
“All solved apart from the (erroneous?) SIDE DRUM. Looked up SIRE DRUM but 24d soon put paid to that.”
Exactly my experience. Agree that the cluing for 29 seems off. Enjoyable but difficult puzzle!
I agree with CrypticSue except my anagram solver did not have a lot of the themed answers in its dictionary. So, I had a lot of use of the crossword solver, a fairly pointless exercise.
Had to do the same as cryticsue above to complete this puzzle.When I got MELODICA, I knew the theme immediately.
Thanks Gozo and PeeDee.
As a musician I knew most of the instruments, except ATABAL. For 30a I thought of “boxers” instead of “Boers” for fighters? AMRITA was new to me.
Hi Jeff,
BOxERS is much better. I wasn’t very happy with Boers but it was the best I could think of. Thanks for that.
Once again I am in awe of Gozo’s ability and skill in the construction of his grid. All across answers of a king and yet no funny odd words for the downs.
Thanks Gozo and PeeDee
Strangely my first answer in was OBOE and the theme immediately became obvious – not that it helped with some of those obscure ones ! It never ceases to amaze having done puzzles, quizzes, etc for a very long time, the amount of things that one still doesn’t know of a subject such as instruments !
Enjoyed the puzzle, more from the learning and reverse parsing / working out a version of an anagram to then have to check that it was in fact a word … and that it was an instrument.
Didn’t know AMRITA and had to look up how a Welsh MP got involved then recollect the Beatles song.
After getting through all of the hard ones, the more common LEGAL AID was the last to go in.