Related Clues:

• Drain-opening stuff
• Threatened layer
• Imperiled layer
• __ layer
• A high flier may fly in it
• Oven cleaner component
• Eco-worry
• UV blocker
• Ultraviolet ray absorber
• Soapmaking caustic
• Important type of layer
• Electrical storm byproduct
• Bleacher
• Sensitive layer
• Ultraviolet radiation absorber