Seafood demand beset by concessions (8)
I believe the answer is:
scallops
'seafood' is the definition.
(I've seen this before)
'demand beset by concessions' is the wordplay.
'demand' becomes 'call' (call is a kind of demand).
'beset by' means one lot of letters goes inside another ('beset' could historically mean 'cover').
'concessions' becomes 'sops' (sop is a kind of concession).
'call' inserted inside 'sops' is 'SCALLOPS'.
(Other definitions for scallops that I've seen before include "Molluscs with wavy-edged shells" , "Curves forming a wavy edge" , "Edible molluscs" , "Seafood" , "Tasty shellfish or ornamental curved edgings" .)