Not sure what you mean by clutch return mechanism, but your bike has a clutch throw-out mechanism which is the assembly mounted on the transmission case and is the gizmo that your clutch cable attaches to. Likely it is miss-adjusted, or possibly even assembled incorrectly. If assembled correctly, most should be adjusted so nearly all of the slack in the mechanism is removed.
Make your cable completely loose, so it does not impact adjusting the mechanism. There is a jam nut and a screw on top of the assembly. It is on the left side, under a little cover with two screws. Loosen the jam nut, and adjust the center screw in and out until you feel it meet resistance. When it does, all the play will be removed from the throw-out mechanism. Back it off about 1/4 turn, hold it in place and lock it down with the jam nut. Make sure your side case covers are correctly and completely installed with all the screws and all tight first.
Some mechanisms can be assembled incorrectly. When you take the side case cover off with the clutch cable still installed, look at the mechanism. With the clutch hand lever released, the cable wire should make an acute angle with the operating arm - like 60 or 70 degrees. When you pull the lever half way, it should be somewhere around 90 degrees, and when pulled it in all the way it should be maybe 120 degrees. This can vary, but you should see that the operation is similar to this description. The arm is attached to a cam with four steep spiral threads and when you pull the hand lever, it rotates and pushes against the clutch disengaging it. (the clutch is engaged when you pull the lever and are in gear, stopped. It is DIS-engaged when the lever is released like when you are driving and the engine is coupled up with the transmission driving the bike along.) Some mechanisms can be put together mismatching the spirals, so check that the cable looks like the previous description. Your bike also has a single ball bearing that is part of the operating mechanism. It goes between the clutch push rod and another part inside the clutch itself. If you ever removed the push rod, it is possible for the ball bearing to roll out unnoticed, so pull out your push rod and make sure it is in there.
