Fire at from the air (6)
I believe the answer is:
strafe
'fire at from the air' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for strafe that I've seen before include "Attack from low-flying aircraft" , "Spray with gunfire" , "Faster (anag.)" , "bombing raid" , "Fire from the air with machine guns" .)