I have to agree with koalar, the only play is supposed to be on the propshaft splines to allow different lengths Wehn suspension is travelling up and down. The movement at the coupling end is a cause for concern as both ends of shaft are supposed to be fixed.
If it's popped out you would need to just unbolt one end, inspect it's not broken and give it a good shoove to snap it back in place, fingers crossed this is all thats needed
If the clip is broken it might be a world of pain, finding a replacement and getting the damaged bits out may not be that easy
I think removing the prop is a start, then you should be able to see what you’re dealing with
If you can’t get the bits, especially things like clips/snap rings, I would imagine a good workshop/plant/engineering supplies would be able to match up