Cambelt is every 72 OR 5 years. A lot of people seem to neglect the latter notes but it is time critical as well. It's pretty expensive for 'just a Clio', a dealer will pull you pants down for about 6-700 just for a belt change. Personally I'd expect to pay about £500 for a belt change complete with major service from a decent specialist.
Some people moan about the gearboxes, but depends how they've been looked after.
Just make sure it's been serviced properly, preferably at a decent specialist, but the important thing is get a good test drive in as you'll soon notice anything not right.