Across:
   1. Bites bulb, getting shocked and becoming most lively (9)
   6. Over and out? Indeed, I left! (5)
   9. Declare negotiations over, wrapping up without detail (7)
  10. All too often select "heads" when taking on University, and not bat first  (7)
  11. Gulf accessed first by steamship (5)
  12. It is briefly pursued, caught and punished (9)
  13. Type of competition for beauties without a waist is, um, strange? (8)
  15. Sped madly, overtaking while being overtaken (6)
  18. Sort of calendar originally just using leap in every fourth solar rounding (6)
  19. Some confess; some take back 23 (4 4)
  22. Arranged croft more carefully for dummy (9)
  24. Dancing near a venue (5)
  25. Slower part confused a Terminator (7)
  26. Doctor, this is the same either way ... embarrassing! (7)
  27. One might be nervous when new, and yell hysterically (5)
  28. Clues he'd developed with start of definition programmed (9)
Down:
   1. Prohibits carrying food for the needy (7)
   2. Saucy performer blew nanny - thrill old even go for! (5 4)
   3. Birds in large sanctuaries (5)
   4. Lice, etc. all over top of coat, picked up from various sources (8)
   5. Edison perhaps capturing hydrogen atoms in motion (6)
   6. After level start to trek, you finally start to ascend, and then oddly come to pass (9)
   7. Barrels ensured rum securely contained (5)
   8. "Better dead...?" Red so feared! (7)
  14. A schooner should be ordered to sway her (9)
  16. Dull awe, not shock, turned provider for 9 5 18 down? (9)
  17. From a sax disruptor to viola heretic, although finally a pioneer on 7 (3 5)
  18. Michael who danced in a black fedora and jocks, an original! (7)
  20. Climbed across top of dune, getting damaged by heat (7)
  21. Sort of nasty weather to horribly toss around marine? (6)
  23. Within backward, male dominated fashion industry, main role for woman? (5)
  24. Silly daleks left out as requested (5)