(historical) a person who is part of the machinery/organization of a Communist party;
e.g. He served as an apparatchik in the government for many years before finally retiring.
(noun)
(humorous, often insulting) a person who serves as an official or member of a large organization, such as a government/political system or a corporation, and who is blindly devoted to the organization;
e.g. In an administration, an apparatchik helps to implement policies without questioning them.