operative - noun

a person secretly employed in espionage for a government

someone who can be employed as a detective to collect information

operative - adjective

• being in force or having or exerting force
• relating to or requiring or amenable to treatment by surgery especially as opposed to medicine
• effective; producing a desired effect
• (of e.g. a machine) performing or capable of performing

operative - thesaurus

functional   pi   running   shamus   sherlock   surgical   working