Possible Clues:

• Agents following in this way Liberal Party
• Flipping English cram onto perfect Greek island, visiting nightclubs etc
• Function of lost, first-class Greek island going all the way back
• Word before 'contract' or 'construct'
• Function opening 11 down
• Thus American spies left an informal gathering
• Is tense leaving communist party
• Group that’s very large including agents abroad
• Word before 'media' or 'network'
• Cola is served up in informal gathering