Across:
   1. Such high musical source requires low treble setting (4 5)
   6. He and Helen ran off to city where pairs travel (5)
   9,18. One subject to murder (penultimate scene) frequently has pointy things on head, hence this relic? (5 2 6)
  10. Liquid fuel in lamp, white heat evenly achieved (7)
  11. Jazz finally incorporated into Metal (4)
  12. Mocked man involved with poodle (9)
  14. Anne rued disaster not of her making (8)
  16. Shocked that Kabul residents took time to remove new foreign leaders
  18. see 9
  20. No good enabling moves, but only about one every hundred weeks or so (8)
  23. Found his tables turned (9)
  24. Owed the leader: two can play at this! (4)
  26. Lust is confused when love involved, king becoming holy man (2 5)
  27. Tel Aviv resident realising loss of last two problematic (7)
  28. Affirmation found pursuing hollow "sight for sore eyes" (5)
  29. Wild and remote feature of 6 across (5 4)
Down:
   1. Hunch one worked in the 1 across of 29 in reverse? (4)
   2. Like one raised with pride, or one broken and kept in line? (7)
   3. Reverse cut contained in garment of 26 (5)
   4. If I were L, dancing would be better for partner (8)
   5. Provide another tag for meaner moves (6)
   6. Instrument made opera ping (4 5)
   7. Change and tour small building (7)
   8. Not going anywhere... perhaps Peter and Paul not well? (10)
  13. Vehicles conveying sober religious instruction, they help hold up the church (10)
  15. Boast U-turn easily managed in such vehicles (9)
  17. Anti-socialist hit, grist for the mill? (8)
  19. Overcome latest dip in expenditure (7)
  21,25. Delicate lie about famous piece of 6 across (3 2 2 4)
  22. Taxman mentions him, in slow movement (6)
  24. Beg ridiculous group to get back to some slow music  (5)
  25. see 21