Geranium macrorrhizum , any of that group, and they are virtually evergreen too. You will probably find Ingwersen's variety or Bevans or Czakor or Spassart as the most readily available types and all will do the same job.

Hardy geraniums came to my mind too. Also aubretia, or oregano (though that's inclined to spread inconveniently).

epimediums will also fit the bill.

I note lots of suggestions for shade loving plants, but I got the impression you wanted a low growing plant to shade the roots of your clematis, which would suggest its actually a sunny area. If that's the case, Campanula muralis, Helianthemum (whatever colour you fancy, come in white, orange, red, yellow and everything in between), Arabis ferdinandi-coburgi, Ophiopogon nigrescens (black grass, yes, its evergreen, low growing and it flowers) or Iberis sempervirens.

Thank You folks
I will take this list when I visit my garden centre next week