That depends on how much damage it has done to the stems and which Clematis it is. One of the early flowering, prune only to remove dead material types might be worth doing, but later flowering types which are cut to the ground or so in February could be pruned now instead with no harm.

Hi MrMate,

Owdboggy is right of course, it all depends what type you have there. If it's a viticella or other type 3 (mostly later flowering clems), just cut it back, as it will grow new shoots from under the ground next year. If it's type 2, do retie it because these kinds don't respond well to wind damage, and broken stems can result in disease getting in to the plant and causing wilt. Type 1 clems (those flowering before June) don't need to be pruned at all unless they get too big, and in this case should be pruned straight after flowering. If you prune them now, it won't kill them, but you won't get flowers next year. So, if it is an early flowering type, I would tie it in again and try to avoid losing much of the growth if you can. Could you tell us what clematis it is please? Ideally, all your clems should be tied in to the trellis or other support as they grow in order to avoid wind damage. It's a slog, but it's worth it!