A military outfit needs some ammunition (4)
I believe the answer is:
unit
'a military outfit' is the definition.
(I've seen this in another clue)
'some ammunition' is the wordplay.
'some' indicates the answer is hidden within the clue (some parts of the word are used).
'UNIT' is hidden within 'ammunition'.
'needs' acts as a link.
(Other definitions for unit that I've seen before include "Individual component" , "Body of soldiers" , "Small group" , "Kitchen element?" , "Whole - group" .)