A person professionally trained by a government to conduct intelligence operations may be called an intelligence officer.
Notes on verification
Well corroborated by official government (MI5), academic, and encyclopedic sources; definition is standard and uncontested terminology.
Sources
- Espionage (en.wikipedia.org)
- https://www.mi5.gov.uk/how-spies-operate (mi5.gov.uk)
- https://police.siu.edu/ci/cuis/im-intel-operatives.php (police.siu.edu)