The best way to understand your own idea better is to explain it to someone else. The more often you explain it, the better you'll understand the idea yourself.
Find someone who is new to this dream you have, and explain the basics. When asked, take every opportunity to explain the high level version of your dream. You'll find it gets easier to explain every time you do.
Don't just hang out in the high-level thoughts of your idea. Once you've had those initial conversations, you'll find a few people that are really easy to talk with about it. They'll like it, and even want to participate with you in it.
Once you've identified these people, start working on explaining the sub-ideas that support the main vision. Since you no longer have to explain the basics, you'll have more time to talk the deeper elements of you dream with them.
I had one of these conversations today. The person I was talking with had been a part of the process, so he didn't need the basics anymore. He understood where I was coming from, so I was free to think through a couple of sub-ideas with him. I now have some great direction on where to take one of the projects that supports my dream.
Have you experienced clarity after explaining an idea?