The fish, kid, will be rising! (3)
I believe the answer is:
gar
'the fish' is the definition.
(type of gar)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for gar that I've seen before include "Type of fish" , "something fishy here" , "swimmer" , "Creature" , "Pike-like fish" .)