Order placed in shop -- husband missed seafood! (7)
I believe the answer is:
scallop
'seafood' is the definition.
(scallop is a kind of seafood)
'order placed in shop husband missed' is the wordplay.
'order' becomes 'call' (calling is a kind of ordering).
'placed in' indicates putting letters inside (I've seen this in other clues).
'husband' becomes 'h'.
'missed' is a deletion indicator.
'shop' with 'h' taken away is 'sop'.
'call' inserted within 'sop' is 'SCALLOP'.
(Other definitions for scallop that I've seen before include "one may be in one's shell" , "Shapely dish" , "Shell - sign of a pilgrim" , "Shellfish - pilgrim badge" , "Mollusc or lacy edge" .)