Paint 2 coats over the clock, paint the inside of the clock with gesso and let dry.
Use the finger to smudge small amount of contrast colour the outside of the clock, let dry.
Apply the colour more dark contrast to let some clear colour exposed and highlight with white gesso (as snow!).
Apart emboss a winter scene (2 pieces) on card stock, paint it with sparkle colours, highlight areas, iridescent glitter, houses, snow, etc.
Use hot glue to secure the glass of the clock inside the front of your clock.
Attach embellish, ribbon, etc on your clock.
Don’t forget to ensure the glass firmly!