Suggestions on repairing a wall clock frame...

I think you are on the right track with making a mold of the undamaged portion. If you did that with a flexible material (silicone or latex) then made the repair with a two-part epoxy, I think that would work. Look on Amazon or at Lowe's/Home Depot for the materials and be sure to follow the directions carefully. I bet you can get that fixed in no time! (By the way, what a deal!)

What about some black electrical tape?

1. Slather a section a little larger than the hole with vasculine on the clock.
2. Make a silicone cast. Make sure the entire area is covered with silicone caulk.
3. Use fiberglass fabric to stuff inside the hole. Use glue to make it stick flat inside as you need a base for the fix.
4. Vasculine the cast and pour plaster (dry wall or plaster-of-paris) inside. After it's dry you may need to cut the original mold to get to your new piece. You can use caulk to attach.
5. Sand out any rough spots and add to any gaps.
6. Paint and seal with polyurethane.

This is plastic. It is probably not work fixing. You could place the works inside another clock box, or if you can hang it so it is not seen (the break is on the bottom is that correct?) just use a good strong tape like duct tape, matching the color as much as possible and cover up the break so dirt does not get in.

How about

I would take the back off, lift the face and the workings, then transfer those to an oval frame. You won't lose the character of the clock that you like, while putting it into a more durable mount.

I say duct tape...then paint the brown color.

I would hot glue some pretty silk flowers in and around the cracked area, and maybe one flower opposite that area. I would probably paint the whole frame anyway, because it doesn’t look like real wood anyway. ☺️

Take it apart and rotate the frame so the broken part is at the top, hang it up and drape a garland over the top.

hope it works

thank you! i bought a huge metal clock with a beautiful face i did not secure it correctly, it fell and cracked Your idea was Great i turn the frame around and put a dainty spray of flowers where it broke Beautiful you saved my clock and it looks great!