A factor in espionage (5)
I believe the answer is:
agent
This clue might be a double definition.
'a factor' is the first definition.
(I've seen this in another clue)
'espionage' is the second definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'in' is the link.
Can you help me to learn more?
(Other definitions for agent that I've seen before include "Operative" , "One acting on behalf of another" , "envoy" , "Actor" , "One who acts for another" .)