Drinker's comeuppance leaving grand house (7)
I believe the answer is:
hanover
'house' is the definition.
(House of Hanover, European royal house)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for hanover that I've seen before include "Royal house from George I to Victoria" , "German 22 Across" , "foreign city" , "German town, and royal house" , "Royal house from 1727" .)