Dont think it is? Most turn brown at the bottom but a picture would help also which Clematis do you have?

If your clematis is bare and brown for the first 3-6 foot or so, but with plenty of healthy growth at the top, it's likely one from the viticella group, which flower from mid June through to autumn - these should be cut down to 2 buds, or about 8-10 inches from the ground in February. This forces shooting from the base or just above, and you have less dead brown stuff to look at during summer.