Bart with bun changed party game (4,3)
I believe the answer is:
bran tub
'game' is the definition.
Both the answer and definition are singular nouns.
Maybe you can see a link between them that I can't see?
'bart with bun changed' is the wordplay.
'with' means one lot of letters go next to another.
'changed' indicates anagramming the letters.
'bart'+'bun'='bartbun'
'bartbun' is an anagram of 'BRAN-TUB'.
'party' is the link.
Can you help me to learn more?
(Other definitions for bran tub that I've seen before include "Lucky-dip container" , "Gifts from here" , "Container for lucky dip" , "place for a dip" .)