Swimmer in Spain known to accept Cockney aid? (7)
I believe the answer is:
eelpout
'swimmer' is the definition.
(eelpout is a kind of fish)
'spain known to accept cockney aid?' is the wordplay.
'spain' becomes 'e' (abbreviation for Espana).
'known' becomes 'out' (as in news which is 'out').
'to accept' indicates putting letters inside.
'cockney aid?' becomes 'elp' ('help' - synonyms - said with the 'H' dropped - a cockney accent.).
'e'+'out'='eout'
'eout' placed around 'elp' is 'EELPOUT'.
'in' acts as a link.
(Other definitions for eelpout that I've seen before include "Burbot" , "Small broad-headed cold water fish - up to lee (anag)" .)