Clues marked '*' share an unstated definition as directed by 4 down

Across:
   7. Frame Nicolas Cage for regressive art (6)
   8. Insulin I'm entitled to have, a treatment which is topical (8)
  10,24dn. * Mad Florida mum turned red (Republican) (4 1 3 6)
  11. see 15
  12. see 13 down
  13. Meditation can bring change (4)
  15,11. * Darwin wore storm (4 6)
  16. * He titters... pinny's undone! (6-4 5)
  20. Osmidrosis doctor not a success in 7! (4)
  22. Without source of nutrients, eat a lot (4)
  23. Bringing back public transport is good thinking (5)
  26. * Lunatic chops, bringing grisly ending (6)
  28. Directs corn (lots directed!) (8)
  29. What separates Old England from New England? Tail can't wag! (8)
  30. * Futurama guy taking ecstasy with kiwi (6)
Down:
   1. In mood I'm in, I shrivel and shrink (8)
   2. Behind screen's enigmatic lead - involvement in devil's work (6)
   3. Error set 7 assistant right off (5)
   4. Director of "stars" (and the man who 5 too 22) is amazing ... do catch her flick! (6 9)
   5. Ken turned! Who first realised? (4)
   6. Country of mango lassi? (6)
   9. Some vermin are tolerated in part of mosque (7)
  14,12ac. * Dish Bert cooked? (3 5)
  17. * Cede crab salad lacks a bit of dressing (7)
  18. Food in ground may come up (3)
  19. Still with zeal, pray manically (8)
  21. Starts where 4's best work was done? (6)
  24. see 10 across
  25. Stuff primarily taken out & placed around opening of nose (5)
  27. Pledge contribution to boathouse (4)