1. Someone who has climbed to a new social class but has yet to be accepted by the social class
2. upstart, newcomer, late arrival, nouveau riche, generally characterized as an ambitious, brash or arrogant person who has yet to integrate with his or her new social group.
… Almost famous people have a tendency to act even more obnoxiously than the famous ones. Graydon Carter, who knows a thing or two about fame, has this parable about a peasant like me arriving in New York from his hamlet and trying to make it in the big city like in a Balzac novel. The provincial enters a dark room and tries to find a door that will enable him to enter another room and so on until he finally reaches success but at each room the door to the next is more difficult to find. Usually in New York society very few arrivistes make it past the first room. I have no idea what he’s talking and it’s probably why his magazine is a giant bore.