The clutch disc (: Kytkinlevy) is a car part which can be found inside the garage at home. It is attached to the clutch cover plate and clutch pressure plate, which are then attached to the flywheel with 6x6mm bolts.
When the disc is worn, it will slip at 4000+ RPM and produces white smoke when accelerating in 1st gear.
To remove it from a clutch cover plate, you first need to remove the clutch cover plate from behind the inspection cover before removing the drive gear. Now the clutch disc can be removed from the cover plate.