upstart

1. N-COUNT You can refer to someone as an upstart when they behave as if they are important, but you think that they are too new in a place or job to be treated as important. 自命不凡的新手[表不满]

Many prefer a familiar authority figure to a young upstart. 许多人更喜欢熟悉的权威人物而不喜欢自命不凡的年轻新贵。