Kind of hard to tell from one picture. It could be a mildew issue or a scorching of new leaves issue but then again I have seen clematis leaves look like this in the early spring and then have them clear up later in the season.

yea..that doesn't look fatal..Some of my clematis do that...usually on the older leaves..it'll be ok...Jeanne

Thanks you 2, I will post if conditions deteriorate.

Some of mine have that look when they have gotten too cold.