Across:
   1. As 10 of great noise, rock drums test horn (13)
  10. Groin is manipulated for roots (7)
  11. Cain's camp perhaps returned somewhere to Israel's north  (7)
  12. Fix up mere bruise mostly with massage (9)
  13. Figure damaged there (5)
  14. see 20
  15. Bill's follower, perhaps, in Mr Deer animation (8)
  18. 8 earned many in the air - in flying sport he was ace (8)
  20,14. Operation run by 8 for British amusement (6 6)
  23. Voter upset with lack of secrecy (5)
  25. Perhaps with the most horn stabs, sire in a bad way (9)
  26. Before breaking clear, lie ready (7)
  27. Less typical is king that is trapped by retreating rook (7)
  28. They addle your senses ... can't her senses be addled? (13)
Down:
   2. Better protected from cold that is right after hot air (7)
   3. Hurl basin about to find bathroom accessory (9)
   4. Make reality right in follow-on (6)
   5. Joined and battled, but I deserted (8)
   6. Domain or section (5)
   7,8. Fighter ace went off playing hand for "Merchant of Venice" (7 3 10)
   9. Those given to questioning or to arresting suspect (13)
  16. Scheme of son is null, just pipe dreams (9)
  17. 8 ran bored operation (3 5)
  19. Mostly nervous wandering, right in swamp (7)
  21. Regularly list terms... in step? (7)
  22. Flier, royal pilot, defeated by 8 (6)
  24. Stoned after joint, proceeding from "hip" (5)