Stuck on a Crossword? Crack the Code of Certain Government Agent, Informally

As a detective, my first step was to analyze the given crossword clue ‘Certain government agent, informally.’ I immediately noticed that the clue referred to a government agent, which indicates that the answer might be an abbreviation or an acronym for a position in the government. Then I focused on the word ‘informally,’ which suggests that the answer could be a slang term or a nickname.