1. Penny amends homework.
PREPARATION - penny P, amends (to make amends) REPARATION.
8. Opening first of louvres in part of church.
CHANCEL - pening (CHANCE), (L)ouvres.
9. Difficult question for model.
POSER - double definition.
10. A hotel - inn arranged without delay.
ON THE NAIL - anagram (arranged) of A HOTEL INN. Didn’t see this at all but it was the only way to hammer in the jigsaw pieces of the anagrist. Looked it up for the blog - (of payments) at once (esp in the phrase pay on the nail).
12. Leader of advance party in trouble.
ADO - (A)dvanced, party (DO).
13. Answer the phone and hear.
PICK UP - double definition.
15. Copper with most unusual habit.
CUSTOM - copper (CU) with an anagram (unusual) of MOST.
17. The writer is going to some trouble.
ILL - the writer (I) is going to do something (I'LL).
18. Let up in respect of crusade.
REMISSION - in respect of (RE), crusade (MISSION).
20. Is stuck in very warm lift.
HOIST - is (IS) stuck inside very warm (HOT).
22. Are all sozzled imbibing English beer?
REAL ALE - anagram (sozzled) of ARE ALL imbibing English (E). Excellent! COD.
23. Discourage one old judge in decline.
DETERIORATE - discourage (DETER), one (I), old (O), judge (RATE).
1. Scheme that initially works.
PLANT - scheme (PLAN) (T)hat.
2. Former scrutineer, reportedly in Treasury department.
EXCHEQUER - former (EX), homophone (reportedly) of scrutineer - checker.
3. At sea, a duck coming in low.
AFLOAT - a (A), duck (O) coming inside low (FLAT - E.G. country).
4. File does not include river snake.
ASP - file - rasp - does not contain river (r) - r(ASP).
5. Immediate flash.
INSTANT - double definition.
6. Conservative knight objected to cornering pointer.
NARROW-MINDED - knight (N), objected to (MINDED) cornering/containing pointer (ARROW). Conservative - definition 7 in Collins - a person who is reluctant to change or consider new ideas; conformist.
7. Professional discharged.
ACCOMPLISHED - double definition.
11. Girl touring island, an American state.
LOUISIANA - girl (LOUISA) touring island (I), an (AN).
14. Musician in small room is close to vocalist.
CELLIST - small room (CELL), is (IS), close to vocalis(T).
16. What could be the beginning, or be my undoing.
EMBRYO - anagram (undoing) of OR BE MY.
19. Marauder blowing top, up in arms.
IRATE - marauder without the top letter p(IRATE).
21. Rocky height in Pretoria.
TOR - in Pre(TOR)ia.