Wash it out real good with warm soapy water first then try some antibiotic salve but you'll have to keep it up where it won't get it dirty till it's healed or might get infection. Watch it close for that.
If you have styptic powder, you can use that to get it to stop bleeding.......if you don't, you can also use baking soda on the wound to get it to stop bleeding (of course this is applied liberally until the bleeding stops).
Keep it clean and put Neosporin or Sylvadine on it. The Neosporin should not have the pain medication added to it. The duck may keep that leg elevated and limp for a couple of days, but other than that it will be just fine. We've had many many mandy duck foot injuries and all heal pretty quick.