Related Clues:

• Kind of brain
• Central part
• Fava or pea
• Ear piece
• Foment
• Annoyance for a princess
• Filbert, e.g.
• Corny bit?
• It may have a black eye
• It rattles around in a whistle
• It's tough to crack
• Cavity
• Pinto or garbanzo
• Pen pal?
• Acorn, essentially