Cryptic crossword No 3,840

Across

1. Regularly doom city reign, sadly, based on faith (9)
2. In old arthouse movie, Luke fought him (5)
3. See 21ac
4. Because of win, leaders of good team wearing rings (5,2)
5. Third note in Dunne composition still in ground (7)
6. Origins of zoonosis are in remote equatorial country in 1976 (5)
7. Builder's helper contacting board before being fired? (7)
8. Basically, 23 down 12 14 (3)
9. Pathogen found in six from Rome and three from Russia (5)
10. Sent mug the wrong way with passes neither to the left nor right (7)
11. Question medical authority (3)
12. Hopefully you only suffer its fire briefly ... or not eternally! (5)
13. Study with Cambridge University, as let back in (7)
14. Grab in a frenzy at this price! (7)
15. Pride that takes over for "the GOAT"? (3)
16. He covers rise / run formula (7)
17. Something you might treat with seaside arrangement (7)
18. New country shut as U.N. do reform (5,5)
19. A soldier taken on by host starting to worry and stick with power (5,4)

Down

1. Final letter taking on being classified by location (5)
2. Guts in bird - one large and small (9)
3. Somehow straw hides in this murky mixture? (9)
4. Country primarily over north central Angola? (5)
5. Ecosystems often threatened as frontiers shifted (11)
6. Full-on gran genuinely enjoys looking well ahead (4,5)
7. Cryptically "do"... by blood, sweat, tears? (4,5)
8. Exploiting work of genius, with no end of trouble (5)
9. A part of liver turned up 20 (5)
10. Part of kidney exhibited aperture (3)
11. Is that man or rhesus trapped in sorcery involving great loss of 16 down? (11)
12. Parts of lymphatic system start to need dose administered (5)
13. Part of Israel approve genocide essentially returning (5)
14. Some heavy weather mostly in store, accepted by farm dweller (9)
15. A group of musicians working with Queen, as Who left (9)
16. Mapping toxic 30's origins a form of entertainment in the west? (3)