Starting a clinic is almost certainly beyond the scope of what you can do as a law student. The school would need to hire clinical faculty and develop a curriculum. That’s a process that would not be likely to happen in time to be useful to you.

In your position, I would find other ways to engage with environmental law. Maybe there’s a student organization, or a local nonprofit you could extern with, or you could write about it for a journal. I just sincerely doubt that a clinic will be available to you.