Mother's run? Not entirely (3)

I believe the answer is:

mar

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'mother's run? not entirely' is the definition.
I can't tell whether this defines the answer.

'mother's run?' is the wordplay.
'mother' becomes 'ma' (Ma is another word for mother or mum).
'run?' becomes 'r' (cricket abbreviation).
'ma'+'r'='MAR'

Can you help me to learn more?

(Other definitions for mar that I've seen before include "Spoil or deface" , "Spoil stuff" , "Cause harm" , "Disfigure" , "wreck" .)

I've seen this clue in the Evening Standard.

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