Stinkers beginning to rile swimmers (7)

I believe the answer is:

rotters

'stinkers' is the definition.
('rotter' can be a synonym of 'stinker')

'beginning to rile swimmers' is the wordplay.
'beginning to' suggests taking the first letters.
'swimmers' becomes 'otters' (otters swim).
The initial letter of 'rile' is 'r'.
'r'+'otters'='ROTTERS'

(Another definition for rotters that I've seen is " Contemptible folk".)

I've seen this clue in The Daily Express.

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