Related Clues:

• "The very ---!"
• Sneaking suspicion, e.g.
• Starting point for an invention
• Head light bulb?
• Intangible spark
• 'If at first, the ___ is not absurd, then there is no hope for it': Einstein
• Something thought up
• Start of something big, usually
• It might be right or bright
• Something that can't be patented
• Inventor's inkling
• 'Drawing is putting a line round an ___': Henri Matisse
• English for 47 Across
• Toon light
• Sudden thought