Related Clues:
- Flash in the brainpan
- Certain germ
- Mental invention
- Bright thing?
- "Whose bright ___ was this?"
- Crossword constructor's germ
- Innovator's inspiration
- Invention starter
- Mental germ
- Basis of an invention
- Invention genesis
- Sudden fancy
- What a light bulb sometimes signifies
- Inventor's springboard
- "The very ---!"