Feeling around swimmer (3)
I believe the answer is:
eel
'swimmer' is the definition.
(eels swim)
'feeling around' is the wordplay.
'around' says the answer is hidden in the clue.
'EEL' is hidden within 'feeling'.
(Other definitions for eel that I've seen before include "Large elver" , "Slippery character" , "Snakelike fish" , "Slippery figure" , "Slippery creature" .)