Exaggerate on account of the party (6)
I believe the answer is:
overdo
'exaggerate' is the definition.
(synonyms)
'on account of the party' is the wordplay.
'on account of' becomes 'over'.
'the party' becomes 'do' (do is a kind of party).
'over'+'do'='OVERDO'
(Other definitions for overdo that I've seen before include "Carry to excess" , "Cook wrongly" , "Sum of a persons actions (Hinduism)" , "Cook too long or act excessively" , "Put too much effort into" .)