I'm glad to see this question - we have a clematis which is as high as the
garage (growing up the front of it), however we need to paint so it will
have to be cut back - how much can I cut it back? We cut back a honeysuckle
severely on our patio in July last year as we were having new windows put in
& it is now growing beautifully again.

I don't know which variety the clematis is but it is starting to get purple
flowers on it - it is quite woody though.