Attack from the air in last RAF effort (6)
I believe the answer is:
strafe
'attack from the air' is the definition.
(I've seen this before)
'in last raf effort' is the wordplay.
'in' indicates a hidden word.
'STRAFE' can be found hidden inside 'last raf effort'.
(Other definitions for strafe that I've seen before include "Attack with gunfire in faster way" , "Spray with gunfire" , "Attack from the air with machine guns" , "Attack with fire from a low-flying plane" , "Attack with machine-gun from the air" .)