Small airship or barrage balloon (5)
I believe the answer is:
blimp
I believe this clue is a double definition.
'small airship' is the first definition.
(I've seen this before)
'barrage balloon' is the second definition.
(I've seen this before)
(Other definitions for blimp that I've seen before include "aircraft" , "Small nonrigid airship" , "needs cover when shooting" , "Small barrage balloon" , "Pompous type - barrage balloon" .)