Backing for each swimmer in disgrace (8)
I believe the answer is:
reproach
'disgrace' is the definition.
(thesaurus)
'backing for each swimmer' is the wordplay.
'backing for' is a reversal indicator.
'each' becomes 'per'.
'swimmer' becomes 'roach' (roach is a kind of fish**).
'per' reversed gives 'rep'.
'rep'+'roach'='REPROACH'
'in' is the link.
(Other definitions for reproach that I've seen before include "Scold(ing)" , "Chide" , "Express disapproval or disappointment" , "approval? Just the opposite" , "criticise" .)