and welcome to the forums
Renaults use Torx heads for most if not all the screws on thier cars.(keeps the ford boyracers off them
if you have a clio there should be a multi-bit tool in the spare wheel tray, next to the tyre wrench and jack.
it will be either grey or black handled with at least 2 bits (long metal bits 5 inches long or so.) there will be one with a torx bit on each end and another with torx and flat blade and maybe another with x2 philips heads.
be carefull not to over strain them when undoing or tightening up, as they can rip the screwdriver ends up.
as they are not tempered steel bits.
as an afterthought, is the water behind the glass of the headlamp, as i dont think they come off, is the rubber cover on the back of the headlamp unit? if water is inside the lamp unit, you may need to remove the entire lamp and drain it let it dry out and refit. there is also more than one screw holding it on, they might be one under the headlamp as well (but im unsure as i dont have a clio)
have you got the haynes manual yet, its always usefull to have a copy for your car. most librarys have a stock of them as well
do a search on the forum here for clio headlamps, there may be a thread regarding your problem.