Superstar, I party! (4)
I believe the answer is:
icon
'superstar' is the definition.
(I've seen this before)
'i party' is the wordplay.
'party' becomes 'con' (abbreviation for Conservatives**).
'i'+'con'='ICON'
(Other definitions for icon that I've seen before include "Sprites" , "Representation, religious say" , "Admired figure" , "Venerated picture" , "Coin (anag)" .)