Over Revving Problem

I have an over-revving problem with my Mark 1 Clipper. When i push the accelorator down towards the floor, my engine sounds like its over-revving and the car doesn't actually accelerate, but just carries on at the same speed. It seems to be getting worse and I am having trouble going up hills. I fear that I could be my clutch, but someone mentioned that there is a part in the engine that may need cleaning. Does anyone know what this might be or has anyone had a similar experience?

Many thanks in advance

have you done anything in the engine bay recently?
anything at all?

if not then it does sound like you clutch has gone!