Due to a research gaffe, one of the answers is the name of a fairly obscure "celebrity" (posthumously) celebrating a milestone birthday, but will probably be more familiar as the name of a particulary famous person NOT celebrating such a milestone!

Across:
   1. Mysterious lost rap beats (7)
   5. Unsettled, do manic stuff (7)
   9. Jumps on unusual lapse (5)
  10. Call to mind lost cello, ceremonially returned (9)
  11. Exploding Python character's core moves, toes having been destroyed (8)
  12. Redo it, with changes? That's her job! (6)
  14. In returned letters, girl briefly finds her reflection with her fellow in 3 (4 9)
  18. Famously, homemaker's major creative endeavour: hurry and battle with time! (6 7)
  20. Bad retro railway uniform (6)
  22. Yanks last bit off bird breast (8)
  25. During dispute, mentioned will (9)
  26. Japanese 24 is OK as a change (5)
  27. Tyres' running direction changed to provide room for smaller ones (7)
  28. Kim's Red Terror looked smug (7)
Down:
   1. Public service post which protects leaders of industrial complex? (6)
   2. Someone 5 across perhaps? All revert to dance (9)
   3. Band is nothing in its current state (5)
   4. Cut version most rate 'G' is thanks to someone planning ahead (10)
   5. Lovely 24 (4)
   6. Australia mar "dole", making some get returned... an emotional rollercoaster! (9)
   7. Stayed back to start getting naughty (5)
   8. They provide food to people and stray alley animals found around Queens (8)
  13. People rue industry now primarily being controled by deviously subtle plans (10)
  15. Sticking forehead, her encephalitis yielded (9)
  16. Vehicle from batch compromised in cyberattack (9)
  17. Fluid combination of Big Bird and Simba perhaps taking second (8)
  19. Lads in trouble, as no man was said to be (6)
  21. Incredible trove made public, or rather one bit of it! (5)
  23. I make a sad sound about 26 turning 25 (5)
  24. Scar with this buildup can make something precious (4)