dci 100 is a sound car, im running one remapped to 130bhp/190lb/ft, give my 172 a run for its money!
dci clios arnt well liked on this forum your better off on cliodci.net however ill answer your questions, but its worth checking out for some more info!
engines are sound, regularly serviced and well looked after they will go on for ever. first ill start with the common clio things to look for, not just with diesels...
pannel gaps & boot floor for sign of crash damage
leaking rear dampers causing bad handling, a dci in any variant will be soft suspension wise but it should still handle well, if it doesnt, chances are somethings up.
anti roll bar drop links
leaking sunroofs
as for diesel related stuff, timing belts are due at 72k or 5 years, expect to pay £300 ish to have it done so knock it off if its not.
clutches are sound and strong, they last well over 150k miles if driven on motorway miles, from 1200rpm put your foot down in 3rd, 4th and 5th gear watching the rev counter for the clutch slipping, the turbo starts to boost just under 1500rpm and hits full boost at 2000rpm, so the torque band is from 1800rpm to around 3000rpm, if its going to slip it will slip between that! that will show signs of a hard driven car or possibly a previously remaped car, again this could be used as a bargaining tool if you want to take on the job (expect to pay from £300 to £500 for a clutch change)
they should never show warning lights on the dash when driving, the bottom right hand side light (the engine management) is most commonly the EGR valve needing cleaned, they get blocked up ocasionally.
the centre orange ligt on the dash (the glowplug light) usually indicates an issue with the fuel system, personally unless you know what you are doing with diesels, i would avoid any car with this light on and wouldnt even bother using it as a bargaining tool.
i know them inside out and any questions just give me a shout