Socialist hairstyle for swimmer (3,6)
I believe the answer is:
red mullet
'swimmer' is the definition.
(red mullet is a kind of fish)
'socialist hairstyle' is the wordplay.
'socialist' becomes 'red' (socialism is often associated with the colour red).
'hairstyle' becomes 'mullet' (I've seen this before).
'red'+'mullet'='RED MULLET'
'for' is the link.
(Other definitions for red mullet that I've seen before include "Brightly coloured food fish" , "one's gathered in net" , "Fish -- dull meter (anag)" , "There's something fishy" , "Tasty swimmer" .)