What's drunk up in store? (5)
I believe the answer is:
depot
'store?' is the definition.
(depot can mean a store or warehouse)
'what's drunk up' is the wordplay.
'what's drunk' becomes 'toped' ('tope' can be a synonym of 'drink').
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'toped' in reverse letter order is 'DEPOT'.
'in' acts as a link.
(Other definitions for depot that I've seen before include "Storehouse, repository" , "Storehouse or terminus" , "Headquarters - storehouse" , "Depository for goods" , "Bus garage" .)