Bart with bun ruined party activity (4,3)

I believe the answer is:

bran tub

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'party activity' is the definition.
The definition suggests a singular noun which matches the answer.

'bart with bun ruined' is the wordplay.
'with' is a charade indicator (letters next to each other).
'ruined' is an anagram indicator.
'bart' after 'bun' is 'bunbart'.
'bunbart' anagrammed gives 'BRAN-TUB'.

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(Other definitions for bran tub that I've seen before include "Lucky-dip container" , "place for a dip" , "Container for lucky dip" , "Gifts from here" .)

I've seen this clue in The Sun.

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