A dustup is an argument or scuffle. A controversial veto by the President might cause a political dustup.
Dustup was coined during the late 19th century, from the idea that fighting in the streets would raise some dust — an earlier phrase was kick up a dust, or "cause an uproar." A dustup can be a physical altercation: "After their dustup in the hallway, they were both suspended from school." But it's most commonly used for squabbles, like the dustup between you and your neighbors over your loud music.