Answer:

IDEA

Answer	Crossword Clue
IDEA	Concept
IDEA	"What's the big ..?"
IDEA	Brainstorm

IDEA	Cartoon bubble
IDEA	Clue
IDEA	Gist
IDEA	Inspiration
IDEA	Light bulb, in comics
IDEA	Notion
IDEA	Sneaking suspicion
IDEA	Brain wave

IDEA	Brainchild
IDEA	Brilliant thought
IDEA	Comic light bulb?
IDEA	Free-association tidbit
IDEA	Impression
IDEA	Invention necessity
IDEA	Inventor's seed
IDEA	Inventor's spark

IDEA	It's just a thought
IDEA	Lightbulb, in a cartoon
IDEA	"I have an ...!"
IDEA	Aftermath of a brainstorm
IDEA	Birth of a notion?
IDEA	Game plan
IDEA	It's all in your head
IDEA	It's all in your mind

IDEA	Just a thought
IDEA	Mental picture
IDEA	New wrinkle
IDEA	Something to run up the flagpole
IDEA	Think tank output
IDEA	Thought
IDEA	Gray matter creation
IDEA	Light bulb, in the comics

IDEA	Think piece
IDEA	Brainstorm result
IDEA	Thing symbolized by a bulb
IDEA	"Here's an ... ..."
IDEA	Entrepreneur's need