Has empathy for swimmers after failure (5)
I believe the answer is:
feels
'has empathy for' is the definition.
I can't tell whether this definition defines the answer.
'swimmers after failure' is the wordplay.
'swimmers' becomes 'eels' (eel is a kind of aquatic vertebrate).
'after' says to put letters next to each other.
'failure' becomes 'f' (this might be a standard abbreviation of which I'm unaware).
'eels' put after 'f' is 'FEELS'.
Can you help me to learn more?
(Another definition for feels that I've seen is " Is affected by".)