Possible Clues:

• Imposing doorway
• Left beside a large, imposing gate
• Left a large gateway
• Way-out wine to go with fair amount of 4 down
• Entrance friend eating golden treacle to begin with
• Part of passport allowing entrance
• Left by a student entrance
• It was found behind a filing cabinet on the 7 1/2 floor of a Manhattan office building in the film 'Being John Malkovich'
• Classical entrance
• Left with a letterhead at entrance