a gleam in (your) eye

something that is thought about or planned but not yet started.

I remember when that invention was just a gleam in his eyes.

Etymology: based on the literal meaning of a gleam in your eye (= a sudden expression of an emotion in your eye)

• the silver screen
• the sixty-four-thousand-dollar question
• the sky's the limit
• the sky's the limit.
• the slings and arrows
• the slings and arrows of outrageous fortune
• the small hours
• the small print
• the smart money
• the smoke
• the socks off
• the socks off someone
• the soft sell
• the something of dreams
• the something of your dreams
• the spectre at the feast
• the spirit moves
• the spirit moves you
• the staff of life
• the stage is set for
• the stage is set for something
• the state of play
• the status quo
• the story of life
• the story of someone's life