Look up Clematis Wilt just to check. Otherwise it won't like the fact that sun is beating on its root crown - put some rocks of some size around it to shade the plant base. Also the soil looks dry in your pictures - mulching should help with that, by shading the soil and forming a barrier between the top of the soil and the air.

It is not wilt. But it could very well be uneven watering. Clematis like a consistently moist root run. This is why you often hear the recommendation for 'roots in shade; tops in sun'. It is not really the shade they require but shade does help to slow soil moisture evaporation. Clear out that weedy area surrounding it and either use a good thick mulch or plant lower, spreading perennials at the base. Or use flagstones or larger rocks as suggested. Anything to keep the sun off the area immediately surrounding the roots. And check frequently in very hot, dry weather to make sure the soil at some depth stays moist.