The throw our bearing is lubricated with grease. But after a few years when the grease reduces, the bearing starts making a whirring noise which goes away when the clutch is depressed.
It might be time to overhaul the clutch. If the clutch plate and pressure plate checks out fine then you might just need to replace or lubricate the bearing.
The only sure way to tell is by opening and inspecting the clutch.
