Gust caused by missile? (4)
I believe the answer is:
scud
I believe this clue is a double definition.
'gust' is the first definition.
(I have seen 'Gust of wind ' mean 'scud' so perhaps 'gust' could also mean 'scud')
'missile?' is the second definition.
(I've seen this before)
'caused by' acts as a link.
(Other definitions for scud that I've seen before include "(E.g. cloud) race along" , "Move along quickly and smoothly" , "Gulf war missile" , "Move along smoothly - run before gale - Russian missile" , "Move fast, missile" .)