Certain mammals — planet contains five pairs perhaps (7)

I believe the answer is:

martens

'certain mammals' is the definition.
(furry mammals in the genus Martes)

'planet contains five pairs perhaps' is the wordplay.
'planet' becomes 'Mars' (Mars is a planet).
'contains' indicates putting letters inside.
'five pairs perhaps' becomes 'ten' (five lots of two).
'mars' placed around 'ten' is 'MARTENS'.

I've seen this clue in The Times.

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