Across:
   1. Aspire to get to old Iran (6)
   5. Going away from London may not be too good! (8)
   9. They give the go-ahead for the first course (8)
  10. Harsh saint leads Bible study? About time! (6)
  11. "Hi!" hailed Lapp in US city (12)
  13. It takes eons to form prominent feature (4)
  14. Harmless n-n-notice (8)
  17. Give workers a gratuity - it's official! (8)
  18. Confused rats leave sinking ship? Maybe not these (4)
  20. Catching taxi after I get left in shared accommodation (12)
  23. Poet's watch is about right (6)
  24. Work together to bury bad cat! (8)
  25. Knight has a smile about Ms Gardner (8)
  26. Greet South African music maker (6)
Down:
   2. Swallows a set mixture (4)
   3. Reduce punishment for having no visible means of support? (9)
   4. Emil runs into rescuers with girl (6)
   5. I'd assist group to express frustration (15)
   6. Wesley Short holds back cowboy pictures (8)
   7. Fight for a bit? (5)
   8. Tonic written about in diary may be needed by solver (10)
  12. Testing driving around Northern Ireland (10)
  15. Tom corrected herald in church (9)
  16. Returning on A1, long before morning, to find flower (8)
  19. Sailor has a setback and eases off (6)
  21. Mother holds key to core material (5)
  22. Billy Connolly may be in second bed (4)