secret service

secret service (plural secret services)

1. A governmental agency that deals with espionage and other acts of secrecy.
   • 2016 February 23, Robbie Collin, “Grimsby review: ' Sacha Baron Cohen's vital, venomous action movie'”, in The Daily Telegraph (London):

     On the surface, the film is a globe-trotting gross-out caper in which Nobby, who's from a hellish version of the titular Lincolnshire town ("twinned with Chernobyl"), is reunited with his long-lost brother Sebastian (Mark Strong), who has become a spy for the British secret services.