An upstart or newcomer; nouveau riche; parvenu; an ambitious, brash or arrogant person who has yet to integrate with his or her new social group.
A person who has risen, climbed up, or has been promoted to a higher social class, especially through acquisition of wealth, privileges, or political authority but has not gained social acceptance by those within that new class.
Being a parvenu; also, like, having the characteristics of, or associated with a parvenu.