secret agent       
noun [ C ] uk/ˌsiː.krət ˈeɪ.dʒənt/ us/ˌsiː.krət ˈeɪ.dʒənt/
 特工;间谍
a government employee whose job involves getting secret information about the governments of unfriendly foreign countries
 Synonyms: operative spy 
See also: agent (SPY)