that's an idea!

that's an idea

That idea could work. A: "We could ask my brother to play music for the wedding." B: "Yeah, that's an idea. Do you think he'd be interested in that?"
See also: idea
Farlex Dictionary of Idioms.

ˈthat’s an idea!

(spoken) used to reply in a positive way to a suggestion that somebody has made: Hey, that’s an idea! And we could get a band, as well.
Farlex Partner Idioms Dictionary
See also:
  • that's an idea
  • bounce an idea off (of) (one)
  • bounce an idea off someone
  • put (something) in (one's) head
  • put (something) into (one's) head
  • put in head
  • put something into someone's head
  • abstract idea
  • toy with
  • toy with (someone or something)