Possible Clues:

• Half-hearted council holds money back
• It's not so hot for the pet to get up here before I would
• Unenthusiastic leader of party in parliament shown up
• Girl given something "not just for Christmas" turning unenthusiastic
• Just above room temperature
• Unenthusiastic and unruly youth penning letter
• Lukewarm feeling Heath has about Greek character
• Indifferent
• Starts to tackle each puzzle inattentively - definitely half-hearted
• Lukewarm food served up, including pie crust