After climb, fancy a wild party (7)
I believe the answer is:
shindig
'a wild party' is the definition.
(I've seen this before)
'after climb fancy' is the wordplay.
'after' means one lot of letters go next to another.
'climb' becomes 'shin' (to shin can mean to climb up something).
'fancy' becomes 'dig'.
'shin'+'dig' is 'SHINDIG'.
(Other definitions for shindig that I've seen before include "wild party" , "Noisy disturbance" , "Lively party, knees-up" , "Rumpus" , "Large and noisy party or quarrel" .)