A very enjoyable romp through Crosswordland which took 9 minutes. Finished in the SE with 20dn. Some crisp clueing and enough mental gymnastics to make this a challenge whilst also being quick.
1. Ruler's talk seems all right initially (4)
TSAR - (Talk) (S)eems (A)ll (R)ight.
4. A court visit upset campaigner (8)
ACTIVIST - a (A), court (CT), anagram (upset) of VISIT.
8. Country lads love Niamh's clothes (8)
SLOVENIA - the answer is 'clothed' in lad(S LOVE NIA)mh.
9. Reduce church work (4)
CHOP - church (CH), work (OP).
10. Grain, local, the French buy finally (6)
BARLEY - local (BAR), 'the' in French (LE), bu(Y).
11. In flexible way making provision (6)
SUPPLY - double definition.
12. Modern territory frequently linked with courage (5-2-3-3)
STATE OF THE ART - territory (STATE), frequently (OFT), courage (HEART). COD - I just liked the surface and the way the parsing clicked together.
16. Reveal contents of text by model (6)
EXPOSE - contents of t(EX)t beside model (POSE).
17. Idiosyncrasy of returning book unopened (6)
FOIBLE - of returning (FO), book unopened b(IBLE).
19. Song, popular, I adapted, in part (4)
ARIA - in part of popul(AR I A)dapted.
20. Long-distance traveller, name, international players recalled (8)
SPACEMAN - the parsing is all backwards (recalled) - name (EMAN), international players - caps (SPAC).
21. Both sides in the Rugby like nice fabric material (8)
TERYLENE - the two outer sides of (T)h(E) (R)ugb(Y) (L)ik(E) (N)ic(E).
22. Fish aunt prepared (4)
TUNA - anagram (prepared) of AUNT.
2. Saucy dance? (5)
SALSA - salsa is an example of a dance and is also a sauce - making it 'saucy'. Possibly an &lit - not being a Strictly fan (it's not so much the dancing as all the dramatic razzmatazz and the seemingly dodgy voting) I am only dimly aware that this is one of the Latin American dances and so possibly considered saucy in the 'sexy' sense.
3. Note your rival - somehow radically different (13)
REVOLUTIONARY - anagram (somehow) of NOTE YOUR RIVAL.
4. Irritate using a word of refusal in New York (5)
ANNOY - a (A), word of refusal (NO) inside New York (NY).
5. Poles in characteristic passage (7)
TRANSIT - Poles (NS) inside characteristic (TRAIT).
6. US politician's weakness over gift I'd put in (4,9)
VICE PRESIDENT - weakness (VICE) over (above - this is a down clue) gift (PRESENT) with I'd (ID) put inside it. I liked yesterday's Morten Moreland cartoon which weaved commentary from US politics with the sad news of Dave Prowse - https://www.thetimes.co.uk/edition/comment/morten-morland-times-cartoon-november-30-2020-m0wdjkwxd
7. Special fuel, I hesitate to say, that's given away too much (7)
SPOILER - special (SP), fuel (OIL), I hesitate to say (ER).
10. Vehicle, one held in reserve, coming up (3)
BUS - one held in reserve - sub - coming upwards in this down clue (BUS).
13. After ex moves, having no liability to Revenue (3-4)
TAX-FREE - anagram (moves) of AFTER EX.
14. Keep an eye on poetry in Old English (7)
OVERSEE - poetry (VERSE) inside Old and English (O E).
15. Draw neckwear item (3)
TIE - double definition.
17. Contrive dishonest outcome of snooker game (5)
FRAME - double definition.
18. Commit to memory name of king, northern (5)
LEARN - name of king (LEAR), northern (N).