Across:
   8. 15 17 star, good on-baller (6)
   9. Bold letters I printed (8)
  10. A bull never defeated without protection (10)
  11. Story telling and lying? Excellent starts! (4)
  12. Electrify wire, then bleach (8)
  14. Old world rue revolution by naked dopes (6)
  15,17. Splendid show by team sees rest beaten (6 6)
  19. 15 17 star keeps energetic, repeatedly marking in telling leads (6)
  20,1dn. 15 17 star rough, or catches poorly (5 3 6)
  23. Arithmetic concept mostly luxurious (4)
  24. 6's students wrecked this, or Chappell's (10)
  26. Karenina has ten... ultimately the worker has just two (8)
  27. Cool store where I can easily buy heads ... and a hug and a kiss! (6)
Down:
   1. see 20 across
   2. Arithmetic concept mostly happening (4)
   3. Derry proud: no regular practice! (3 3)
   4. 15 across 17 star who was frightening on the pitch (3 4)
   5. Most inclined to steer right clear of nuisance (8)
   6. Oddly, they're surrounded by affirmations, finally for the old days! (10)
   7. Before place's leaders, likely I loom large indeed! (8)
  13. Boss makes start awkard (10)
  15. Providing a break to primary school study (8)
  16. Game in first grade? (8)
  21,18. 15 across 17 star moving on OK... score time! (6 7)
  22. He had a hand in many characters, with layers working (6)
  25. Inside any minds...? (4)