It is probably not dead. It will probably sprout out again unless it was dug up.

They respond favorably to hard pruning.

I thought my Josephine was gone (was ill last year) ~ completely died to the ground ~ she never did in the past 10 years ~ this early onset of Spring she came back in 2 tiny baby plants ~ pinched & well watered she kept growing! However the *Chlorosis* diagnosed last year is back & she's getting treatments!

Good luck ~ she might come back!!!

It will no doubt come back. when I first moved here 45 years ago, my neighbor burned a Baron Velliard to the ground. Its getting ready to bloom now. My oldest one.
An elderly friend collected $300 apiece for several specimen tree peonies after a car climbed a stone fence and took out a whole row of them.

HeidiClematis - a Clematis can grow 12 feet in a season so yours may well just grow back as it was this year. Were you not pruning it down annually anyway?

On the other hand what on earth was your neighbour doing touching your plants?