Cancel — not pause — mucking about (5,2,4,3)

I believe the answer is:

clean up ones act

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'cancel not pause mucking about' is the definition.
I know nothing about this answer so I cannot tell whether this works.

'cancel not pause mucking about' is the wordplay.
'cancel not pause' can be anagrammed to 'CLEAN UP ONES ACT'.
But, I'm not clear how this is indicated.

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I've seen this clue in The Times and The Sunday Times.

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