Salt fish for fussy eater (4,5)
I believe the answer is:
jack sprat
'fussy eater' is the definition.
(I know that Jack Sprat is a fussy eater)
'salt fish' is the wordplay.
'salt' becomes 'jack' (both can mean a sailor).
'fish' becomes 'sprat' (sprat is a kind of fish).
'jack'+'sprat'='JACK SPRAT'
'for' is the link.
(Other definitions for jack sprat that I've seen before include "fat-free dieter" , "He ate no fat" , "Nursery-rhyme character" , "His wife could eat no lean" , "One leaving fat" .)