operative

a person secretly employed in espionage for a government

someone who can be employed as a detective to collect information

being in force or having or exerting force; "operative regulations"; "the major tendencies operative in the American political system"

relating to or requiring or amenable to treatment by surgery especially as opposed to medicine; "a surgical appendix"; "a surgical procedure"; "operative dentistry"

effective; producing a desired effect; "the operative word"

(of e.g. a machine) performing or capable of performing; "in running (or working) order"; "a functional set of brakes"