Related Clues:

• Viola's range
• Light bulb's signification, in cartoons
• Light bulb, in comics
• Mental glimmer
• Object of thought
• Head piece?
• Creator's sine qua non
• Enrico Caruso, for one
• Andrea Bocelli, for one
• Brainchild
• Theory
• It comes to a head
• Saxophone type
• Creative nugget
• Exclamation point?