You can buy a clock kit at the craft store. All you have to do is make a hole somewhere in the painting and then fit the clock attachment through it. I did a similar project with a drum: https://www.craftylittlegnome.com/drum-clock/
Michael's has clock kits. I made lots of those over the years.
I bet you could do something similar to this except with your painting instead of old table top: https://www.hometalk.com/36897654/how-to-make-a-giant-diy-wall-clock-from-a-tabletop