Whale that sleeps with one eye open (4)

I believe the answer is:

orca

(Other definitions for orca that I've seen before include "Killer in deep" , "Sea creature" , "Large predator" , "27 [WHALE]" , "Killer at sea" .)

I've seen this clue in the USA Today.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.