Iif you jack up one of the front wheels and put the car in a gear, then try and turn the lifted wheel you will be able to see if the drive-shaft turns, if the wheel turns and not the shaft then its that cv joint, if the shaft turns and so does the other side shaft at the same time then its the other side cv joint, if only one shaft turns then the fault is either in the gearbox or the clutch,to fix the clutch the gearbox will have to come out anyway . . hope this helps

Its the clutch if you can select gear with the engine running without pressing the clutch then its the clutch itself.