Captain I see heading for boat (4)
I believe the answer is:
ahab
'captain' is the definition.
(Captain Ahab appears in Moby-Dick)
'i see heading for boat' is the wordplay.
'i see' becomes 'aha' (both are said after realising something).
'heading for' says to take the initial letters.
The first letter of 'boat' is 'b'.
'aha'+'b'='AHAB'
(Other definitions for ahab that I've seen before include "He hunted Moby Dick" , "Jezebel was wife of this King of Israel" , "Captain of the whaler Pequod" , "one who hunted whales" , "Jezebel's husband, wicked king in the 'Old testament'" .)