Lass finally catching game, unaccompanied male (4)
I believe the answer is:
stag
'unaccompanied male' is the definition.
(man attending a social event without a woman)
'lass finally catching game' is the wordplay.
'finally' indicates one should take the final letters.
'catching' is a charade indicator (letters next to each other).
'game' becomes 'tag' (I've seen this before**).
The final letter of 'lass' is 's'.
's'+'tag'='STAG'
(Other definitions for stag that I've seen before include "one may get in a rut" , "Horned animal" , "Male-only" , "Deer; with only men" , "involving men" .)