ACROSS
 8. <besotted> ENAMOURED = DEMEANOUR*
10. A FE outside IR = AFIRE <burning>
11. TO PM _O_ ST = TOPMOST <first>
12. GOA HE + AD = GO-AHEAD <approval>
13. <marching band composer> SOUSA = SO USA
15. RAN + G ELAND = RANGELAND <savanna>
17. <anarchist slogan> NO GODS NO MASTERS = (GOODNESS MATRON'S)*
20. ←NA MELD + DIM← = MIDDLEMAN <go-between>
22. <love> AGAPE <struck>
23. KIPPER after S = SKIPPER <sea-captain>
25. <notices> SIGNAGE = ←GANG IS← E
27. "ISLE" = AISLE <passage in church>
28. RAUNCHIER* = HURRICANE <storm>

DOWN
 1. <eject> JETTISON = JET (IS NOT)*
 2. CA MP = CAMP <political faction>
 3. (.e)CO-ROMAN DEL(f.) = COROMANDEL <ebony>
 4. <monks> BRETHREN = (.m)BRE THREN(o.)
 5. ←A LAG← = GALA <fancy event>
 6. (MEN CARE)* inside CIA = CINE-CAMERA <filming device>
 7. <squabbled> FEUDED = "FEW DID"
 9. <eat> DIG IN = D_ + I_ GIN
14. <least pious> UNGODLIEST = (SINGLED OUT)*
16. E_ GALATIANS* = EAST ANGLIA <old kingdom>
18. <part of government> MINISTRY = TRY after MINIS
19. <made kebab with> SKEWERED = SK EWE RE _D
20. MAP outside ⭯HIS⭯ = MISHAP <accident>
21. <frontier> MARCH <soldiers' exercise>
24. <spotted> PIED = P IED
26. AX outside J A = AJAX <war hero>