1.
covert operative; secret agent; undercover agent
A person sent by a state or organization to carry out clandestine activity — espionage, sabotage, or influence operations — in another country or group. Almost always used of the other side, never as a neutral job title.
Formed from 工作 (maneuvering, covert operations) plus the suffix 員 (member, staff). Note that 工作 on its own also means "handicrafts" — the school subject — so the covert sense comes entirely from the compound and its context.
Common collocations
Register
The word carries a strong negative charge and is common in news reports and thrillers. Online it is also thrown around loosely as an insult, accusing someone of posting on behalf of a foreign government.