You only hear it turning right because it's only knocking when the joint is bent that way, it's quite normal for CV joints to fail in that way, it's probably split open as GavFre said. The fact it knocks regardless of how hard you're driving makes it more likely it is the CV joint, as your wheels are always turning
I'm guessing the frequency of the knock varies with the speed you're going?
Of course it *could* be something else, but a knackered CV joint is the most likely explanation, you ought to be able to inspect it yourself without too much bother I would have thought to avoid extra garage costs if it's not that, but don't hold me to that as I've never looked at one on a Clio...