Cora, able, massaged swimmer (8)
I believe the answer is:
albacore
'swimmer' is the definition.
(albacore is a kind of fish)
'cora able massaged' is the wordplay.
'massaged' indicates an anagram (I've seen 'massage' mean this).
'cora'+'able'='coraable'
'coraable' is an anagram of 'ALBACORE'.
(Other definitions for albacore that I've seen before include "Variety of tuna" , "fish" , "Large tuna; able orca (anag.)" , "Long-fin tunny" .)