Cold clean bather swimming in complete freedom (5,7)
I believe the answer is:
carte blanche
'complete freedom' is the definition.
(I've seen this before)
'cold clean bather swimming' is the wordplay.
'cold' becomes 'c' (eg on taps).
'swimming' is an anagram indicator (letters swim around into a new order).
'clean'+'bather'='cleanbather'
'cleanbather' is an anagram of 'arteblanche'.
'c'+'arteblanche'='CARTE-BLANCHE'
'in' is the link.
(Other definitions for carte blanche that I've seen before include "Complete discretion" , "total freedom" , "free rein" , "Unrestricted authority" , "Free hand" .)