Anybody use this on a wider neck - 1.75 inches? If so, how far does it go up?

Inside diameter is about 2 1/8"

will this capo fit on a classical guitar ?

yes, i use it on a standard dreadnought guitar. i use it with metal strings though. i see no reason it would not work for other strings.

Could this work for a telecaster with a 7.25 neck?

Yes. The metal bar is pretty much straight, but the plastic cover will conform to the fretboard. I have 2 Strats and 1 Tele...all vintage spec'd necks with 7.25 necks and this is the capo I use on them. I have a Schrubb capo designed for the 7.25 radius and I prefer the Hamilton. In my opinion I find the design of this capo is better because the pressure applied to the strings is equal across the fretboard. To my ears, clip-on capos and the Schrubb apply slight more pressure one side. Others may disagree, but I've found I have to tweak the tuning far less when I move the Hamilton capo around when compared to clip on designs. They are slower to adjust, in my opinion that's their only drawback.

Is there a way to "clip" this onto the guitar like a traditional capo?

if you mean to clip it onto the guitar when not really using it as a capo, ie. storing it for use later, then no. relative to a traditional jaw like capo, this is a slow install and removal and really no way to hook it onto another part of the guitar other than when it is installed on the neck.