Across:
   1,12,13. Novel means of summoning spirits - long sentence by boring sort (5 4 4 10)
   6. see 25 (5)
  10. Mother has request for flower (6)
  11. Prod Iran violently and see what precipitates (8)
  12,13. see 1
  14. Removing cover of thin dust and revealing historic tract (9)
  16. Brutal overseer, typifying historic African leaders (5)
  19. Familiar trick now nightly feature (5)
  20. MS program, or ultimately sly contributor to criminality (9)
  23. He writes massive amounts about Mr Hobbit shedding exterior (3 7)
  25,26,27,6. Steady hands grasp music book (4 8 3 3 5)
  28. Penned? We penned nonsense! (5)
  29. Proud organisation remains focused despite losing one (9)
Down:
   2. Princess replaces crusty leader in grip of old habits (9)
   3. Restraint shown in role as headmaster (5)
   4. Smart after facebook reaction to copycat fashion (8)
   5. For majority, a timeless land (7)
   7. Crazy, ridiculous, deranged, "one short"! (9)
   8. Join union despite overseer's objections? (5)
   9. Added note about rogue players in sex trade  (5)
  15. Complete directions for crossword answers (9)
  17. Charm her hose... so devious! (9)
  18. Updates dining hall times (8)
  21. Illegal operators working in the red (7)
  22. To bar development? (5)
  24. Nose ring not much fun (5)
  25. Minor player in sex trade (5)