Swimmer more sexy for Cockneys (5)
I believe the answer is:
otter
'swimmer' is the definition.
(animal which swims)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for otter that I've seen before include "Something furry" , "Mammal, 'Tarka'" , "Water-loving animal" , "Playful aquatic animal of 'Tarka' fame" , "Lithe swimmer" .)