Vulgar party game (8)
I believe the answer is:
baseball
'game' is the definition.
(I know that baseball is a type of ball sport)
'vulgar party' is the wordplay.
'vulgar' becomes 'base' (base can mean vulgar or crude).
'party' becomes 'ball' (ball is a kind of party).
'base'+'ball'='BASEBALL'
(Other definitions for baseball that I've seen before include "Predominantly North American game" , "Game played badly in the sable lab" , "Summer sport of US" , "SPORT/GAME" , "Lea blabs about the sport" .)