Devotee I party with afterwards (8)
I believe the answer is:
idolater
'devotee' is the definition.
(someone devoted to idols)
'i party with afterwards' is the wordplay.
'party' becomes 'do' (do is a kind of party).
'with' is a charade indicator (letters next to each other).
'afterwards' becomes 'later' (synonyms).
'i'+'do'+'later'='IDOLATER'
(Other definitions for idolater that I've seen before include "One admires" , "Tailored to worshipper of graven images" , "devotee" , "great admirer" , "One worshipping graven image" .)