its constant velocity joint on the inner end of your driveshaft, ull pay about 50 quid + for the joint depending on where u go..fitting could cost anything upto 100 quid again depending on where you go..theres a fair amount of work involved in changing it
thats assuming it is the inner cv, thats just what went n mine, the casing gets damaged allowing alot of play on the driveshaft thats whats clicking i would think