As above that's your radiator support, they're shit and all do that.
If your car is less than 12 years old you can claim against Renault (prepare for a battle).
Or the 4 options are
1) Wheeler Motorsport for an aluminium one (so won't rust), but it doesn't have the legs that go to the subframe, so you can't put on the undertray (well you will have to make something to attach the rear of the undertray to) they're £150
2) buy a new one for Clio RS, can't remember price, but I'm sure it was more than £200
3) buy a non-genuine one for a non-RS Clio, they're like £70, but they need modifying, you need to drill out the mount that the radiator sits on and put it where it should be for RS versions (using your current one as a template), then weld that on and paint
4) buy another used one, will end up similar to yours after a few years