Across:
   1. Provider of treats perhaps who talks too much (7)
   5. Chemical chop: ram was modified (7)
   9. Wryly funny, losing right to be charged (5)
  10. Your own writing for oralising? (9)
  11. Performing arts can't perform (8)
  12. Was uncomfortable, not starting out married (6)
  14. You might sign it or sing it (4)
  15. Big spending tiger a flop after restructuring (10)
  18. Special instrument developed trimmer core (10)
  19. American lesson is not new (4)
  22. Point to the point (6)
  24. Comprehensive cleaning job (8)
  26. Given role: traitor or thief of nuts (9)
  27. "Sound of Silence" perhaps? (5)
  28. Scant clothing on little lackeys (7)
  29. In places, marketing people are animated little things (7)
Down:
   1. Recorded number at end of legal document (7)
   2. Amazing soft drinks - half sweet (9)
   3. Maniac clouts insect (6)
   4. Cue D.C.: error in motion came up again (10)
   5. Cheat sleep here (4)
   6. Amazing tax, in taking one in three to keep working (8)
   7. Heartache at having to give up the open country (5)
   8. What's left sure die out (7)
  13. Reward fast work later (10)
  16. Missing having can when not indulging? (9)
  17. 27ac.  might feature cornet parts in company (8)
  18. Bit of method with timeless maxim (7)
  20. Picks infantry (7)
  21. It shows itself when it is lost (6)
  23. It won't dissolve in water or rinse out (5)
  25. Love to sit back being a musician? (4)