Concession about name for shellfish (7)
I believe the answer is:
scallop
'shellfish' is the definition.
(scallop is a kind of shellfish)
'concession about name' is the wordplay.
'concession' becomes 'sop' (sop is a kind of concession).
'about' indicates putting letters inside.
'name' becomes 'call' (a name is a call-sign).
'sop' going around 'call' is 'SCALLOP'.
'for' acts as a link.
(Other definitions for scallop that I've seen before include "Marine bivalve" , "Shapely dish" , "Bivalve mollusc with fan-shaped shell" , "Seafood - shell" , "Shellfish that's also plc" .)