Related Clues:
- Comic-strip light bulb
- Brain matter?
- Invention's beginning
- It may pop into your head
- Entrepreneur's starting point
- New thought
- Reason to shout "Eureka!"
- "Hey, what's the big ___?"
- Invention inspiration
- Flash in the brainpan
- Certain germ
- Mental invention
- Bright thing?
- "Whose bright ___ was this?"
- Crossword constructor's germ