RAF in set to change attack (6)
I believe the answer is:
strafe
'attack' is the definition.
(I've seen this before)
'raf in set to change' is the wordplay.
'in' is an insertion indicator.
'to change' indicates an anagram.
'set' with letters rearranged gives 'ste'.
'raf' inserted inside 'ste' is 'STRAFE'.
(Other definitions for strafe that I've seen before include "Blast, shell" , "Shoot at from plane" , "Spray with bullets" , "Attack with gunfire in faster way" , "Make 'Raking Fire'" .)