After midnight, general enjoyment (4)
I believe the answer is:
glee
'enjoyment' is the definition.
(I have seen 'Impish enjoyment ' mean 'glee' so perhaps 'enjoyment' could also mean 'glee')
'after midnight general' is the wordplay.
'after' means one lot of letters go next to another.
'midnight' becomes 'g' (the middle letter in 'night').
'general' becomes 'Lee' (Robert E. Lee - US revolutionary commander).
'g' put next to 'lee' is 'GLEE'.
(Other definitions for glee that I've seen before include "Unholy delight" , "Type of club" , "Great delight; part song" , "Old English part-song" , "(Malicious) satisfaction" .)