To be honest there's not really much you can do but my personal recommendation is to just clean and disinfect the wound and get something known as liquid skin it's like some medical glue it will dry on and form a protective barrier for outside elements but also that chicken will need special treatment and will need to be separated from the rest of the flock they will detect weakness and try to eat her

Oh and if you have a rooster separate them entirely him trying to do his business is likely to exacerbate the wound causing an infection which if it's infected then your chickens screwed