Clematis wilt - thanks
 

Thanks very much for all the replies, especially for the link to the website
which is very informative. I think I shall cut it right down and hope a new
shoot appears. My garden is heavy clay and I do have problems with snails
(when there is any rainfall), so that could be some of the problem. I'll
let you know if it eventually recovers.

Best regards,

Aileen from Notts