cloak-and-dagger | meaning of cloak-and-dagger in Longman Dictionary of Contemporary English | LDOCE

From Longman Dictionary of Contemporary Englishcloak-and-daggerˌcloak-and-ˈdagger adjective [usually before noun]    SECRETvery secret and mysterious, and usually involving the work of spies  a cloak-and-dagger operationExamples from the Corpuscloak-and-dagger• His enthusiasm for the cloak-and-dagger business of detection seemed to have waned.• He was arrested after a cloak-and-dagger operation involving the CIA and MI6.