Across:
   1. Religious leader's grabbing? Case dismissed, having no direction (5)
   4. I chose local drunk to take first taste of speed from - no drug addict(9)
   9. No tsunami actively peaks (9)
   10. Scottish child is essential to Alba Irn-Bru (5)
   11. I quit crowdfunding platform and receive shade (6)
   12. One who could diagnose 18 illegally obtains treatmeant at last (8)
   14. Vera abruptly interrupts Spirit Talk, leading to breakup (9)
   16. About to get rid of this type of fever (5)
   17. Demand Doctor Dre wears gold (5)
   19. A Newcastle twosome, actors - not dancers - decidedly English comedy leaders! (3 3 3)
   21. Energy company unplugged; that's efficient (8)
   22. Large shirt for the circus (3 3)
   25. Mathematician the Spanish backed in Western half of Europe (5)
   26. Singer from Two Directions (5 4)
   27. Absurd pottiness of those who give legs up (9)
   28. Regal member held back from foreplay... orgasming (5)
Down:
   1. Dead body intended for display? It's still uncertain (7 2 2 4)
   2. Form briefly around a French border (5)
   3. Value, for example, in Bury (7)
   4. Eager to chop statue's head off (4)
   5. Cartridge holding empty oil, perfume or food container (10)
   6. That man with women's underwear? One principally cautious of Jewish people (7)
   7. Retired, call up regularly ignoble duke (4 2 3)
   8. Marxist concept in persistent upper case (8 7)
   13. Badly paint one otorhinolaryngologist surgeon's head for hospital guests (10)
   15. Terribly, I vocalised (not as) softly for short film (5 4)
   18. Initial reaction; to upset after cause of fungal disease (4 3)
   20. Three in disarray? None of the above (7)
   23. Article prefacing gutless route to get muscular (5)
   24. Core of Observer article originally spotted in Times (4)