y-come-lately [noun] [C] [disapproving] - a person who starts a job or activity later than other people and who is thought to use the experience and knowledge of these people to try to obtain an advantage over themWhen he was given a managerial post, many of his colleagues were annoyed that this johnny-come-lately had been given such a swift promotion.
JOHNN
Meaning of JOHNN in English
Cambridge English vocab. Кембриджский английский словарь. 2012