Across:
   7. Current measure of musical equipment (4)
   8,22dn. Energy lost in error, say? Alas, faulty ones powered 12 (5 6)
  10. Country's U.N. seat even taken away (3)
  11. Illegal war U.N. led legally? (5 3)
  12. After time and energy spent, key 21 27 for 10 14 19 (6)
  13. Ease of new user's corruption (5)
  15. Was "union" missing from hub, as in something they couldn't have on 12? (9)
  18. Worked on my tax? A sorry task that could be done on 12 (1-3 9)
  20. Birth of nice pinto, dotty (9)
  21. Great time had in second final (5)
  24. One vote against zero for 10 14 program (6)
  26. Brit POWs trained in one part of craft (8)
  27. Including favourite opening of departed (3)
  28. Part of 29 to reorient? (5)
  29. Wild orgy which may cause a change of attitude on 14 19 (4)
Down:
   1. Planet six five one used to deliver 12 (6 1)
   2. Webmaster's pride's hurt (6)
   3. Lyrical part of the bible, major line with viper coming up (5)
   4. Sophocles mostly worked around king's early education centre (9)
   5. Firstly divide up total, and finally pay tax (4)
   6. Wisdom of professor Carl, mostly urban (8)
   9. Ultimately fail to damage fellow with big hammer part where 12 operated (3 5 5)
  14. Destination reached from Canaveral, or assorted capes (5)
  16. Strange to all, land that's mostly lagoon (5)
  17. 12 had a velcro one, as confused Rat and Pig in D&D (9)
  18. Australian senator grinding axe: no phone! (8)
  19. Wandering, is not at post (7)
  22. see 8 across
  23. Celebration of a charge? (5)
  25. Flit about to get what 1 gave 12 (4)