Complete
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7 14 19 1 9 12 21 2 15 3 11 20 10 4 18 16 5 8 13 6 17
  1. 1a American crime syndicate, having close relations with the Sicilian Mafia (4,6)
  2. 7a Grandfather, say (or a grandfather clock?) (3-5)
  3. 8a Nibble (4)
  4. 9a Electrical sound (4)
  5. 10a First artificial Earth satellite, orbiting from October 1957 to January 1958 (7)
  6. 12a Chimney climber and repairer (11)
  7. 14a Small acting role (3,4)
  8. 16a Crossword arrangement (4)
  9. 19a Complain(t) (4)
  10. 20a Australian state formerly known as Van Diemen's Land (8)
  11. 21a Antics (10)
  12. 1d Star (abbr) (5)
  13. 2d That will teach you! (2,5)
  14. 3d Denomination (4)
  15. 4d Shell fragments (8)
  16. 5d Prove to be false (5)
  17. 6d Endangered (2,4)
  18. 11d Drink before a meal (8)
  19. 12d Name of Ho Chi Minh City until 1976 (6)
  20. 13d Medium for radio and television broadcasting (7)
  21. 15d Puss In Boots, for example (abbr) (5)
  22. 17d Supernatural being, the object of worship (5)
  23. 18d Scandinavian capital, called Christiania until 1925 (4)