Swimmer takes little time these days (6)
I believe the answer is:
minnow
'swimmer' is the definition.
(minnow is a kind of fish)
'little time these days' is the wordplay.
'little time' becomes 'min' (short for minute).
'these days' becomes 'now' (I've seen this in another clue).
'min'+'now'='MINNOW'
'takes' acts as a link.
(Other definitions for minnow that I've seen before include "Very little fish" , "nobody" , "Very small freshwater fish of the carp family" , "A fish; insignificant person" , "Small fry" .)