Auctioneer carelessly spilling sweetheart's drink (9)
I believe the answer is:
cointreau
'drink' is the definition.
(type of liqueur)
I don't understand how the remainder of the clue works.
(Other definitions for cointreau that I've seen before include "A sweet orange-flavoured liqueur for cautioner" , "Alcoholic drink" , "Sweet orange-flavoured colourless liqueur" , "Orange liqueur" .)