Undercover agent (4)
'undercover agent' is the definition.
(mole is a kind of undercover agent)
This is all the clue.
(Other definitions for mole that I've seen before include "Furry burrowing animal" , "Spy; burrower" , "sauce" , "Skin blemish and burrowing animal" , "Small burrowing animal" .)
'undercover agent' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for spy that I've seen before include "Undercover agent" , "Catch sight of" , "Notice" , "One gathers information on enemies" , "One who collects secret information as for government" .)