Possible Clues:

• On reflection, went missing over horse - the one taken at Christmas from local
• Source of some December food poisoning
• Drink from island I left - and half of another!
• Fortified drink similar to a flip
• Medal given by heartless king in return for a drink
• Drink similar to advocaat
• Mixed drink, for example, before decoration's put up
• Something warming for Christmas decoration that's put up, for example on top
• Holiday concoction
• Like medal picked up for alcoholic drink