Where to find duty-free dry wine (7)
I believe the answer is:
airport
'where to find duty-free' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'dry wine' is the wordplay.
'dry' becomes 'air' (airing is a kind of drying).
'wine' becomes 'port' (port wine is a kind of wine).
'air'+'port'='AIRPORT'
Can you help me to learn more?
(Other definitions for airport that I've seen before include "Place for planes" , "passenger terminal" , "where flight begins or ends" , "Travel terminus" , "Transport hub" .)