Possible Clues:

• Delicacy from Channel Islands or sea near Cherbourg
• Shellfish occurring in earlier times, but not with frequency
• Female leaving old seafood
• Seafood starter knocked off by ex
• Formerly missing insect shell
• Ear-shell
• Shell that's yellow floating on French sea
• Food from Yellow Sea (foreign)?
• Mollusc, once having been separated from female
• Edible abalone; rhymes with projecting window