Atticus Finch's occupation is incredibly important to this fabulous American novel. Considering your words are what Atticus does "for a living," I assume you are referring to what he does to "bring home the bacon" for the family (i.e. how he makes his money); therefore, I'm afraid being a dad (although just as important, and probably more important) can't be considered what he does "for a living." He is a lawyer and, as such, agrees to defend Tom Robinson in court against the Ewell family who accuses poor Tom of both assaulting and raping Mayella Ewell. Atticus Finch is not only a lawyer, but a good lawyer at that. He uses, as evidence, the fact that Tom Robinson doesn't have use of his left arm to prove that the injuries to Mayella could not have been committed by Tom. In fact, they were committed by Bob Ewell, Mayella's father. Unfortunately, despite Atticus' noble efforts, Tom is convicted anyway.