Free and occasionally funny party (4)
I believe the answer is:
undo
'free' is the definition.
(I've seen this before)
'occasionally funny party' is the wordplay.
'occasionally' means one should take alternating letters.
'party' becomes 'do' (do is a kind of party).
The alternate letters of 'funny' are 'un'.
'un'+'do'='UNDO'
'and' is the link.
(Other definitions for undo that I've seen before include "Loosen (knot)" , "Free from ties, laces, etc" , "Cancel or reverse an action" , "Loosen; annul" , "Reverse effect of" .)