Related Clues:

• Sponge cakes right for composer
• Arctic Ocean peril
• Sort of lettuce you see little of in the main
• Main hazard
• Lettuce having hidden depths?
• Frozen piece of Arctic lake captured by enemy
• Big chunk of the North Atlantic?
• Recalled diving bird going behind one cold Arctic feature
• Floating ice hazard
• Arctic ice chunk
• Enemy crossing lake ice
• Large lump of ice in the sea
• Ice chunk in the sea
• Titanic striker
• Variety of salad vegetable -- only its tip's usually taken in