Chickens are incredibly resilient and even though it looks bad, it doesn't appear life threatening...imo. Clean the wound with the wash of your choice, hydrogen-peroxide, beta-dine, saline solution, etc.. Then apply an antiseptic such as blu-kote, vetericyn, neosporine, etc. I like Blu-kote because it seems to disguise the wound from other chickens and they don't pick at it. I would separate her for a day or two, but then try and get her back with her buddies to keep her spirits up. You may need to provide some additional barriers around the kennel for protection because your carnivore will probably be back. Good luck!