Possible Clues:

• You might be green with it
• Desire for what someone else has
• Deadly sin that's a hint to the starred answers' "initials"
• "To feel ___ is human, to savour Schadenfreude is devilish": Schopenhauer
• Covetousness of emissary lacking nothing
• First witness against Faithful in 'The Pilgrim's Progress'
• Sin that Gore Vidal called 'the central fact of American life'
• Green party requirement?
• European navy — not the answer to go green?
• 'Green-eyed' feeling