Mums participating in drama sometimes (3)

I believe the answer is:

mas

'mums' is the definition.
('ma' can be a synonym of 'mum')

'participating in drama sometimes' is the wordplay.
'participating in' says the answer is hidden in the clue.
'MAS' is hidden in the letters of 'drama sometimes'.

(Another definition for mas that I've seen is " Mothers".)

I've seen this clue in The Times.

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