Umm, no reason why the injector should be leaking:S
But i'm sure its possibly come loose either at the head or at the rail end.
Also the pipe may be split, Get the car started and have someone give it a rev, (build the fuel presure up) and inspect the fuel rail area.
The clips to hold the injector - rail can be brought from Renault.....just over £1 each iirc, The 'O' ring cannot, if thease need replacing you may have a job finding some.
if you need 'O' rings you would be best posting on
www.williamsclio.co.uk
sure someone had some contacts on where to buy from.