What do you mean, ants destroyed your clematis - do you mean they made a nest in the pot it was growing in? Or do you mean you saw it crawling with ants on the leaves and stems? If the latter, likelihood is the clematis was infested with aphids, which the ants "milk" for their honeydew, so spray to kill the aphids would have resolved the problem.
Raise your container with herbs off the ground by using either pot feet, or sitting the edges on bits of old roof slate or anything that will give it some clearance underneath. Dust the area underneath with ant powder too.