You don't need a vet... you need to capture the chicken and cover it's face with a towel to keep it quiet and calm. You then need to take a pair of wire nippers/cutters and cut the stalk as close to skin level as you can on the THINNER side of the stalk. That may be above or below. Whichever is the thinner side, that's the one to cut close to the skin surface. Then grasp the other side and pull it out/through to remove it.
Once it's removed, assess the damaged area for damage; bone, muscle, tendon, blood vessels. If bleeding (which I suspect will not be the case), some blood stop powder or sugar, corn starch, etc to help it coagulate and stop. Then apply either blukote or triple antibiotic ointment, iodine, vetricyn, or whatever antibacterial solution you may have available. Make sure she can move her wing naturally. Watch her for a few days to make sure she's recovering properly.
Depending on the extent of the injury, you may want to remove her from the group for a few days, keeping in mind that in doing so, you're almost guaranteeing that she's gonna get picked on even more when you try to re-insert her.
ETA: Best wishes for success and a happy ending.