Zheng Jue passed the imperial examinations in the Jinshi class during Emperor Zhaozong's Guanghua era (898–901).
[1] (It was said that previously, he had failed the Jinshi examinations repeatedly, but Zhang, whom he was depending on (suggesting, but not conclusively indicating, that his father Zheng Hui was deceased by this point), interceded for him with the testing authorities, such that he was given a pass.
)[2] For the rest of the Tang dynasty, he served successively as a copyeditor at Hongwen Pavilion (弘文館), an assistant at Jixian Institute (集賢院), and an imperial censor with the title Jiancha Yushi (監察御史).
With Li Cunxu's army approaching Daliang, Zhu committed suicide, ending Later Liang.
[4] Shortly thereafter, he was slightly promoted to be the military advisor to the prefect of Cao Prefecture (曹州, in modern Heze, Shandong).
Nevertheless, Zhang Quanyi, who had become an honored Later Tang official after submitting to Later Tang, was interceding for him with Li's chief of staff Guo Chongtao, trying to get him made chancellor again; instead, though, he was made an advisor to the Crown Prince — an honorary position as there was no crown prince at that time.
[6] Li Siyuan also gave him the honorary title of Kaifu Yitong Sansi (開府儀同三司) and granted him an estate at Zheng Prefecture (鄭州, in modern Zhengzhou, Henan).