Bubble filled with clear liquid on toe, how should i treat this?

Protect it: Possibly cover with a band-aid so that it doesn't have any friction on it and does not pop. You probably should see a podiatrist to have it checked out and see what the definitive treatment should be.

See : Podiatrist for treatment, may open it and let it draine but concern is possible infection.

Let it pop.: It sounds like you might have a blister. I would recommend letting it pop on its own. Once it does, just treat the area with alcohol or betadine. I do not recommend popping this on your own.