Convenience for mild soldiers (9)
I believe the answer is:
gentlemen
'convenience' is the definition.
(I've seen this before)
'mild soldiers' is the wordplay.
'mild' becomes 'gentle' (similar in meaning).
'soldiers' becomes 'men' (I've seen this before).
'gentle'+'men'='GENTLEMEN'
'for' acts as a link.
(Other definitions for gentlemen that I've seen before include "Convenience" , "of high social standing?" , "Runners" , "Males of refinement" , "Smugglers" .)