I wouldn't try to close it up as that can lead to it ulcerating/gangrene and blood poisoning. I would wash it out 2x a day for the first week with some saline solution/ weak salt water and then once a day after that. keep her away from any other chickens until she is all healed or they will pick at and potentially canabalise her. some antibiotic cream in the wound after washing could also be a good idea