Shucked shellfish (6)
I believe the answer is:
oyster
'shucked shellfish' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for oyster that I've seen before include "Bivalve native" , "Secretive person; bivalve" , "the world may be yours" , "Means to cross London" , "Pearl-producing shellfish" .)