Possible Clues:

• Some cucumber etc that's put on French loaf
• Arty chapeau
• Elizabeth without 'Queen'? Wear that?
• Ingredient in French dressing?
• Said to cover up and get head protection
• Take in Beethoven's 1st quartet; cap that!
• It's often felt in the art world
• Tam's kin
• Soft flat hat
• Deprived, having lost fine item of headwear