Predatory fish (4)
(Other definitions for barracuda that I've seen before include "Voracious tropical fish" , "fearsome swimmer" , "Large predatory sea fish" , "Marine attacker" , "Vicious swimmer" .)
(Other definitions for sharks that I've seen before include "Voracious sea fish" , "Large carnivorous fish" , "Feared fishes, may be basking or hammerhead" .)
'predatory fish' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for pike that I've seen before include "dive in this position" , "Predator with strong teeth" , "Weapon on long shaft; Northern hill" , "Old weapon -- Dad's Army character" , "Long European freshwater predator" .)