Concerned with swimmers, cold (6)

I believe the answer is:

offish

'cold' is the definition.
(thesaurus)

'concerned with swimmers' is the wordplay.
'concerned with' becomes 'of' ('of' can mean 'concerned with' or 'relating to').
'swimmers' becomes 'fish'.
'of'+'fish'='OFFISH'

(Another definition for offish that I've seen is " Aloof, distant in manner".)

I've seen this clue in The Telegraph.

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