You need to wrap and leave it for a few days usually no longer than a week and it should be fine . If your duck is just now growing in it's flight feathers. How old? should be able to find info on youtube on how to wrap for some reason our pictorial isn't coming up.
It could be Angel wing but most times it's just looks that way as the feathers are growing in....I suggest you wait till the wing feathers have come in fully.....
Do not wait, that IS the start of angel wing. It needs to be wrapped asap if you plan to fix it. Waiting until the wings are all grown and it will be too late to fix