Gather men tipsy after party spirit -- such a spoilsport (3,2,3,6)
I believe the answer is:
dog in the manger
'a spoilsport' is the definition.
(thesaurus)
'gather men tipsy after party spirit' is the wordplay.
'tipsy' indicates an anagram.
'after' is a charade indicator (letters next to each other).
'party' becomes 'do' (do is a kind of party).
'spirit' becomes 'gin' (I've seen this before).
'gather'+'men'='gathermen'
'gathermen' anagrammed gives 'themanger'.
'do'+'gin'='dogin'
'themanger' put after 'dogin' is 'DOG-IN-THE-MANGER'.
'such' acts as a link.
(Other definitions for dog in the manger that I've seen before include "One not letting others use what they themselves have no use for" , "possessive type?" , "selfish hoarder" , "that could disrupt nativity play" , "Possessive person" .)