literal meaning or translation: to sit up straight; normally to describe a person who is dying to do something (usually to get promoted at work) and finally manages to get what they want; to be formally raised / promoted to a certain status
Definitions (粵典–words.hk)
動詞
由副手升上去做某個組織嘅阿頭 a deputy of a top position to formally be promoted to that top position