One way to be certain, is take the clutch cover off and push the clutch arm in and see if the clutch plate moves away from the gears. If it does, you'll most likely just need adjust the cable end or you can do small adjustments from the lever "on the handle bars".
If it doesn't it could be the bearing rolled out of the drive gear side or it needs adjusting of the star nut.
I don't like cross linking, but this is one of the better tear downs, "how to" of the clutch I've run across. The second page, post 18 shows a diagram of all the parts. Part 24 is the bearing I refer to.
http://motorbicycling.com/f4/bicycle...lutch-222.html