Related Clues:

• Caruso was one
• "What's the big __?"
• Reason to shout 'Eureka!'
• Luciano Pavarotti, e.g.
• Asset for an inventor
• You might bounce it off someone
• Thrust
• Hunch
• Innovative thought
• Creative notion
• Voice higher than baritone
• It pops into the head
• Invention seed
• Patent seed
• Cause of an ''aha'' moment