Mine do this every year. They start to go brown and crispy from the bottom up and I eventually cut them right down to the ground. They come up ok in the Spring.

The growth looks like that of one planted in a pot - is it in a pot? If so, how deep is the pot, and how long has it been in the same pot?

Earwigs on the flowers and either drought or snails at the base of the plant. Snails scrape away the bark at the base of a stem and so the stem then dies from lack of sap.

Mine are all planted in the garden, and my late sister's garden has one too like the one Complete beginner has. They all, without exception, do this every year. I am sure I read an answer one here once which said that some types of clematis do this. I shall have to find it.

Did you see the small black things on the table? Might this be the problem? It is in a new half barrel and planted this spring. Thank you for all for your inputs.

I did see the small black things - having trouble just by looking at them deciding whether they're simply pollen beetles or aphids, or something else, need a magnifying glass.

Clematis in containers do better if the container is 18-24 inches deep, and if the container is in full sun, with something stood in front to keep the roots cooler by creating a bit of shade, just on the pot. Looks to me as if it might have got too hot or not had quite enough water at some point rather than anything being a serious problem. If the variety you've got there is a late flowering one in the viticella group, they do have a tendency to get bare near the base, and should be pruned back to about 8 inches in winter to try to reduce this problem.