Primarily a teacher,she later became a writer结构 Primarily a teacher,she later became a writer.这句话的前面为什么可以是adv+ a teacher呀

问题描述:

Primarily a teacher,she later became a writer结构
Primarily a teacher,she later became a writer.
这句话的前面为什么可以是adv+ a teacher呀

应该是省略结构吧
就象tired of sth/doing sth,clause