Way to encourage swimmer (8)
I believe the answer is:
sturgeon
'swimmer' is the definition.
(sturgeon is a kind of fish)
'way to encourage' is the wordplay.
'way' becomes 'st'.
'to encourage' becomes 'urgeon' (urging on is a kind of encouraging).
'st'+'urgeon'='STURGEON'
(Other definitions for sturgeon that I've seen before include "Caviare-yielding fish" , "So urgent to find caviare-bearing fish" , "Large fish, valued for its roe" , "Fish yielding caviar and isinglass" , "So urgent to find caviar-bearing fish" .)