They are self adjusting, but the mechanism is known to fail and needs to be manually backed off. I suggest you go to
www.renaultforums.co.uk
The following is just one of many threads on this
http://www.renaultforums.co.uk/showthread.php?t=57945
Search the site, or post a request, for adjustment instructions, or buy the Haynes workshop manual for your car, £20 from Halfords, bookshops etc.
It is, of course, also possible the clutch itself is indeed worn and needs replaced, but I'd be having a look at the cable/adjuster first.
kenny d, February 2010
