Building in garden where a serving of wine is free? (10)
I believe the answer is:
glasshouse
'building in garden' is the definition.
(type of greenhouse)
I don't understand the remainder of the clue.
(Other definitions for glasshouse that I've seen before include "Building for plants; prison" , "where no one should be stoned?" , "stone's throw away?" , "where lapidation is not recommended?" , "Conservatory - military detention centre" .)