Related Clues:

• 'What's the ___?!'
• Possible solution
• Fanciful idea
• ...
• Start of an invention
• Inventor's ''step one''
• Bright one from gray matter
• Inventor's start
• Caprice
• Light bulb's signification, in cartoons
• Light bulb, in comics
• Mental glimmer
• Object of thought
• Head piece?
• Creator's sine qua non