The master has no head for fish (6)
I believe the answer is:
kipper
'for fish' is the definition.
(type of fish)
'the master has no head' is the wordplay.
'the master' becomes 'skipper' ('skipper' can be a synonym of 'master').
'has no head' means to remove the first letter.
'skipper' with its initial letter taken away is 'KIPPER'.
(Other definitions for kipper that I've seen before include "One drops off" , "Smoked split herring" , "Smoked fish" , "Preserved herring" , "has been caught napping" .)