Joan carried on very amusingly (4)

I believe the answer is:

sims

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'joan' is the definition.
Both the answer and definition are singular nouns.
Maybe they are linked in a way I don't understand?

I don't understand how the rest of the clue works.

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(Other definitions for sims that I've seen before include "One who wrote about a Christmas Day" , "Author of 'In the Workhouse: Christmas Day'" .)

I've seen this clue in the Evening Standard.

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