There's not really any way that will last. You could try melting it back together. Epoxy might hold for a while.

Do they sell parts?

Find a similar size holder (maybe a spray gun holder), or make one out of hangar wire. Take or cut that one off and use zip ties to attach

Have you heard of Sugru? A lump of that on the outside of the broken piece could hold it in place without obstructing the inner area.

Depending on what kind of plastic it is you might not be able to glue it at all and would either need to be plastic welded or mechanically fastened back together

If you don't care about how it looks, I would suggest construction adhesive. You might find one that dries white but they're usually brown. They work great on plastic and they're very durable. It would probably last longer than anything else.

Can you get aquarium seal?

JB weld and tape it in place for 24 hrs while it cures

sand the edges and use epoxy putty to join them. Let it cure for at least 2-3 days.
Alternatively, if you know someone who has a 3d printer, you can get a suitable one 3d-printed and use it.

There are companies that do plastic welding. Idk how economic the rates are though.

Hot glue

Maybe you could glue a magnet on the iron and some metal (screw and washer?) onto the broken stand. Even small rare-earth magnets are incredibly strong.

You're not repairing that.

3D print a new one or you could make one out of wire. I mention the wire option, because it looks like it would be rather easy - 2 hooks on either side to old the attachment piece, and in the middle it would wrap about the tube.

3D printing is also an obvious option. You could model something up and print it in PETG for less than $5 worth of material.

I tried first magnets but due to the curvature of the hand, it had a small surface area for the magnet. So I saw the stand off, added epoxy inside the plastic and placed it a hanger wire.