Melville captain (4)
I believe the answer is:
ahab
'melville captain' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ahab that I've seen before include "One whose nemesis was white" , "Husband of Jezebel" , "sea captain" , "Jezebel's husband - Moby Dick's hunter" , "one who hunted whales" .)