The Belt is for seat belt, if the front does not light up, it means that the panel was not intended to have the seat belt light.
As for the clock illumination, you should be able to trace the line on the back of the panel and see if it runs to a separate line on the harness, this line must be connected to the ignition and a suitable diode must be installed in the system.
if your panel don't have the diode then it wasn't meant to illuminate but you can run it yourself, here is the layout,the harness may be different but the kind of wiring is the same.
Look for clock illumination in both below.