Ammunition centre for some soldiers (4)
I believe the answer is:
unit
'some soldiers' is the definition.
(unit can mean a group of soldiers )
'ammunition centre' is the wordplay.
'centre' says to take the centre.
The centre of 'ammunition' is 'UNIT'.
'for' acts as a link.
(Other definitions for unit that I've seen before include "Subdivision of a military group" , "A single self-contained item" , "Single undivided whole" , "Single whole as part of a larger whole" , "Item combining separate parts" .)