At end of evening, general merriment (4)
I believe the answer is:
glee
'merriment' is the definition.
(glee is a kind of merriment)
'at end of evening general' is the wordplay.
'at end of' suggests the final letters.
'general' becomes 'lee' (Robert E. Lee - US revolutionary commander).
The final letter of 'evening' is 'g'.
'g'+'lee'='GLEE'
(Other definitions for glee that I've seen before include "Great delight; part song" , "Jewelled headband" , "Happiness" , "Great pleasure" , "Sort of club" .)