Untried troops accepting assistance (6)
I believe the answer is:
maiden
'untried' is the definition.
(thesaurus)
'troops accepting assistance' is the wordplay.
'troops' becomes 'men' (I've seen this in other clues).
'accepting' indicates putting letters inside.
'assistance' becomes 'aid' ('aid' can be a synonym of 'assistance').
'men' placed around 'aid' is 'MAIDEN'.
(Other definitions for maiden that I've seen before include "First ever public address" , "over, you won't score" , "Unmarried girl of old" , "See 3" , "Single" .)