I see! British captain (4)
I believe the answer is:
ahab
'captain' is the definition.
(Captain Ahab appears in Moby-Dick)
'i see british' is the wordplay.
'i see' becomes 'aha' (both are said after realising something).
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'aha'+'b'='AHAB'
(Other definitions for ahab that I've seen before include "Jezebel's husband - Moby Dick's hunter" , "Jezebel's husband or captain in 'Moby Dick'" , "Fictional whaler" , "He hunted Moby Dick" , "sea captain" .)