Related Clues:

• Gray matter
• Kidney, e.g.
• Wax, for one
• Green or coffee
• Vanilla, for one
• Hit on the noggin
• ''The Law West of the Pecos''
• ... and another
• Think box
• Green veggie
• Certain fiber source
• Coffee or vanilla
• Conk in the noggin
• Coffee source
• First American in space