Shellfish concession receiving visit (7)
I believe the answer is:
scallop
'shellfish' is the definition.
(scallop is a kind of shellfish)
'concession receiving visit' is the wordplay.
'concession' becomes 'sop' (sop is a kind of concession).
'receiving' means one lot of letters goes inside another.
'visit' becomes 'call' (synonyms).
'sop' going around 'call' is 'SCALLOP'.
(Other definitions for scallop that I've seen before include "Shapely dish" , "Shell - sign of a pilgrim" , "Shellfish that's also plc" , "Shellfish - badge worn by pilgrims to Santiago de Compostela" , "Marine bivalve" .)