Mammals stay supple after exercising (10)

I believe the answer is:

platypuses

'mammals' is the definition.
(platypus is a kind of mammal)

'stay supple after exercising' is the wordplay.
'after exercising' is an anagram indicator.
'stay'+'supple'='staysupple'
'staysupple' anagrammed gives 'PLATYPUSES'.

I've seen this clue in The Guardian.

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