US soldier getting married, allowed a cocktail (6)
I believe the answer is:
gimlet
'a cocktail' is the definition.
(gimlet is a kind of cocktail)
'us soldier getting married allowed' is the wordplay.
'us soldier' becomes 'gi' (I've seen this in other clues).
'getting married' becomes 'm' (I've seen this in other clues).
'allowed' becomes 'let' (I've seen this before).
'gi'+'m'+'let'='GIMLET'
(Other definitions for gimlet that I've seen before include "Tool for boring holes and a cocktail" , "A carpenter's tool" , "Small hand tool - cocktail of vodka or gin with lime juice" , "Cocktail of gin, or sometimes vodka, and lime juice" , "Hole borer" .)