Predatory tropical marine fish with strong teeth and a protruding lower jaw (9)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
barracuda
(Other definitions for barracuda that I've seen before include "Large predatory sea fish" , "Voracious marine fish" , "fearsome swimmer" , "Voracious tropical fish" , "Marine attacker" .)