Her acceptance of it makes for mirth (6)
I believe the answer is:
hilary
'her' is the definition.
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for hilary that I've seen before include "The Spring legal term" , "girl or boy" , "Boy's or girl's name" , "University term" , "Term < for a girl" .)