Shellfish from sailor with a sole (7)
I believe the answer is:
abalone
'shellfish' is the definition.
(abalone is a kind of shellfish)
'sailor with a sole' is the wordplay.
'sailor' becomes 'ab' (abbreviation for able seaman).
'with' is a charade indicator (letters next to each other).
'a sole' becomes 'alone' (I've seen this in another clue).
'ab'+'alone'='ABALONE'
'from' acts as a link.
(Other definitions for abalone that I've seen before include "Edible shellfish, sea-ear" , "Ormer, ear shell" , "Edible mollusc - on a bale (anag)" , "Source of mother-of-pearl" , "Sea food must be found" .)