dabac

As long as you keep in mind that your result may vary, and that I don't vouch for the ultimate suitability of the fix.
First, I'd see if it kan be disassembled. Assuming it can, I'd see if it can be shimmed to take the play out or not.
If shimming is possible, I'd do that.
If not, I'd turn it into a rigid. I'd evaluate the amount of gap, clean the fork and then choose a chemical with a suitable gap-filling/capillary action and glue the fork together.
If it's a big gap I'll use a laminating epoxy, maybe even hook up the ol' vac pump to aid penetration.
If it's less of a gap, I'll use one of those special compounds used to mount bushings to stick the fork together.

If it can't be disassembled, it gets trickier. Then maybe drill a hole at the bottom of the fork, flush the fork best as possible using brake cleaner or similar and dribble in bushing mount liquid, or a thicker epoxy depending on gap. Perhaps some more vac pump action.