I'm afraid we're going to need a bit more information. What kind of engine or drive train? In my case, I had a clutch bearing go bad on my Whizzer. That bearing sits in the middle of a pulley that's on the end of an arm that pivots up and down, and the arm is mounted to the rear of the engine. If you look at the photo of my Whizzer, the clutch is located under the part of the chrome belt cover that has the circular cut-outs.
If you're talking about one of the 2-stroke engines (known around here as Happy-Times or HTs regardless of make) the clutch and bearing are internal, on the right hand side of the crankcase.