Related Clues:

• Headdresses
• Haberdashery buys
• They may be tipped in acknowledgment
• Busby and derby
• Milliner's inventory
• Baseball players' toppers
• 'Porkpie' and 'pillbox' attire
• They may be locked on a computer
• They may be passed or tipped
• Mushroom tops
• Baseball headwear
• Big letters, for short (and what your answers must be written in to understand the theme)
• Berets and sombreros
• Dental additions
• Uppercase, for short