Not yet attempted taking on males in need of grooming (9)

I believe the answer is:

untrimmed

'in need of grooming' is the definition.
(as in a hair that needs to be groomed)

'not yet attempted taking on males' is the wordplay.
'not yet attempted' becomes 'untried' (not yet tried).
'taking on' is an insertion indicator.
'males' becomes 'mm' (an abbreviation for male written twice).
'untried' going around 'mm' is 'UNTRIMMED'.

I've seen this clue in The Guardian.

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