Complete
00:00:00
8 10 13 16 6 5 19 1 17 2 9 14 3 11 15 4 12 18 7
  1. 5a Coolness under pressure (9)
  2. 8a Block of ice (4)
  3. 9a Fixed (8)
  4. 10a <span>Colourless gas used as fuel, C</span><sub>2</sub><span>H</span><sub>6</sub> (6)
  5. 11a In a way (4,2)
  6. 13a Tobacco user (6)
  7. 15a Ingratiating (6)
  8. 16a In an earliest stage — evil ramp (anag) (8)
  9. 18a Rational (4)
  10. 19a Black tie or smart casual, for example (5,4)
  11. 1d Skin treatment (4,4)
  12. 2d Burst into flames (6)
  13. 3d Bits of uneaten cake — I'm surprised! (6)
  14. 4d Tree branch (4)
  15. 6d Regulars — consumers (9)
  16. 7d Share set aside (9)
  17. 12d ___ in Blue, 1924 George Gershwin composition (8)
  18. 14d Prepare for an exam (6)
  19. 15d Join the ends together (6)
  20. 17d Gloom (4)