Ocean predator (5)
I believe the answer is:
'ocean predator' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for shark that I've seen before include "(Fishy) extortionist" , "predator" , "Predatory 5 dn" , "Predatory fish (or person?)" , "Voracious fish" .)