Across:
   1. see 3dn.
   9. It's said to come from empty vessels pounding me my grain (9)
  10. see 3dn.
  11. Used 3dn to be groovy (6)
  12. Bandage small 17 down pop star (8)
  14. Big Shaman pig brew - no horse, but frog and newt maybe (10)
  16. Pure instinct has control of 17 (4)
  18. Sell one out of the film (4)
  19. Agent from European nation grabbing his easiest opening (10)
  21. Legal institution profits from those whose price is right (8)
  22. Isaac, moving trilogies (the first one way back) (6)
  25. Famous Edwardian retreat? (5)
  26. Knight of the grail has smile following little look at layer (9)
  27,1dn. Two sound transporting ships pause for fifth month with men & boys suffering skeletal weakness (6 3 6 3 5 2 5)
Down:
   1. see 27ac.
   2. Games put out telepathic reception spectrum (5)
   3,1ac,10ac. What foils foil? (3 3 2 8 4 3 5)
   4. Wrong to proceed from death to birth perhaps (4)
   5. Get thin gin preparation as applied to poor belts  (10)
   6. Like posted confirmation (6)
   7. Overly tough exterior diminished and impotent (9)
   8. Challengers serve nuanced network (9 6)
  13. Insect repellant oil lent car eccentricity (10)
  15. A TV pair to sabotage a player of 26 (9)
  17. An old one may be 7, but two old ones appear here (8)
  20. Stain surrounding oddly dour old god  (6)
  23. Fool satellite with hacker's final intervention (5)
  24. Drop from building (4)