Related Clues:

• Hunch
• Innovative thought
• Creative notion
• It pops into the head
• Invention seed
• Patent seed
• Cause of an ''aha'' moment
• Brain output
• It might come off the top of your head
• Inventor's forte
• Brainy output
• Noodle output?
• Estimation
• Thinker's output
• Its icon is a light bulb