Fish made captain lose head (6)
I believe the answer is:
Here is my best explanation:
'fish' is the definition.
(type of fish)
'captain lose head' is the wordplay.
'captain' becomes 'skipper' ('skipper' can be a synonym of 'captain').
'lose head' means to remove the first letter.
'skipper' with its initial letter taken off is 'KIPPER'.
'made' is the link.