Catapult — night loss (anag) (9)
I believe the answer is:
slingshot
(Other definitions for slingshot that I've seen before include "Sing Holst? (Anag)" , "Weapon American kid may produce" , "enough to knock you out" , "No slights (anag) - catapult (US)" , "Catapult -- thin gloss (anag)" .)