Surprise to get uncapped wine (4)
I believe the answer is:
hock
'wine' is the definition.
(type of wine)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for hock that I've seen before include "Buy property, say" , "Animal joint - German white wine" , "German white wine from Rhineland" , "Dry wine; joint; pawn" , "Pawn a German wine?" .)