double agent

 Longman Dictionary of Contemporary English 5++朗文当代英语 5++LDOCE 5++朗文 5++ˌdouble ˈagent noun [countable]  PMsomeone who finds out an enemy country’s secrets for their own country but who also gives secrets to the enemy 双重间谍 → spy

Examples from the Corpus

double agent• A double agent is, therefore, well placed to achieve this.

ˌdouble ˈagent nounChineseSyllable  

secrets someone an Corpus country’s finds enemy who out

double agent
ˌdouble ˈagent noun [countable]
someone who finds out an enemy country’s secrets for their own country but who also gives secrets to the enemy ⇨ spy

double agentBrE /ˌdʌbl ˈeɪdʒənt/ 🔊NAmE /ˌdʌbl ˈeɪdʒənt/ 🔊 nouna person who is a spy for a particular country, and also for another country which is an enemy of the first one 双重间谍