Perform better than old-fashioned party (5)
I believe the answer is:
outdo
'perform better than' is the definition.
(I've seen this before)
'old-fashioned party' is the wordplay.
'old-fashioned' becomes 'out' (as opposed to 'in').
'party' becomes 'do' (do is a kind of party).
'out'+'do'='OUTDO'
(Other definitions for outdo that I've seen before include "Surpass, go one better than" , "Cap" , "Beat" , "Overtake" , "Surpass - overshadow - excel" .)