Moth circles round American helicopter (9)
I believe the answer is:
eggbeater
'american helicopter' is the definition.
(US slang term)
'moth circles round' is the wordplay.
'moth' becomes 'egger' (egger is a kind of moth).
'circles' indicates putting letters inside.
'round' becomes 'beat' ('beat' can be a synonym of 'round'**).
'egger' enclosing 'beat' is 'EGGBEATER'.
(Other definitions for eggbeater that I've seen before include "Meringue maker's tool" , "Kitchen utensil" , "Kitchen gizmo" , "Whisk" .)