Possible Clues:

• Aid in developing hair waves
• Garment that protects waves
• Garment that preserves hair waves
• Rihanna wore one for a British Vogue cover
• Garment with a cape
• Head-covering garment
• It might be on the floor when you wake up
• *Garment that covers waves
• Closefitting head cover
• "Anyone who has ever worn a ___ spells it '___,'" per a 2018 New York Times article