Wild ligers or young salmon! (6)
I believe the answer is:
grilse
'young salmon' is the definition.
(I've seen this before)
'wild ligers' is the wordplay.
'wild' is an anagram indicator.
'ligers' is an anagram of 'GRILSE'.
'or' acts as a link.
(Other definitions for grilse that I've seen before include "Young swimmer" , "Gel, sir? (anag) - young salmon" , "Young salmon returning for first spawning" , "Young salmon returning to fresh water for the first time" , "A one-year old salmon" .)