Complete
00:00:00
7 14 19 1 9 12 21 2 15 3 11 20 10 4 18 16 5 8 13 6 17
  1. 1a Early form of bicycle (10)
  2. 7a Overcome (8)
  3. 8a Single thing (or two people?) (4)
  4. 9a Roman gent's garment (4)
  5. 10a Penmanship (7)
  6. 12a Readiness to welcome guests (11)
  7. 14a Seriousness (7)
  8. 16a Fourth rock from the sun (4)
  9. 19a Become obstructed (4)
  10. 20a Scottish knitwear design (4,4)
  11. 21a Lack of due care and attention (10)
  12. 1d Arched ceiling (5)
  13. 2d West-central French city — kind of porcelain (7)
  14. 3d Foul substance (informal) (4)
  15. 4d Fatherly (8)
  16. 5d Go with the flow (5)
  17. 6d With enthusiasm (6)
  18. 11d Jocund (8)
  19. 12d Rush headlong (6)
  20. 13d One from Qom? (7)
  21. 15d Fashion (5)
  22. 17d Puzzle out (5)
  23. 18d Billie Jean (née Moffitt, 1943) (4)