Playful swimmer (5)
I believe the answer is:
otter
'playful swimmer' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for otter that I've seen before include "carnivore is concerned" , "Fish eater of the weasel family" , "Good swimmer" , "Fish-eating mammal" , "furry creature" .)