Wine selection from clarets in Athens (7)
I believe the answer is:
retsina
'wine' is the definition.
(type of Greek wine)
'selection from clarets in athens' is the wordplay.
'selection' indicates the answer is hidden within the clue (I've seen 'selection of' mean this).
'RETSINA' can be found hidden inside 'from clarets in athens'.
(Other definitions for retsina that I've seen before include "Greek white wine flavoured with resin" , "Flavoured Greek white wine - nastier brand" , "S European wine" , "Type of Greek wine" , "Greek wine - nastier sort" .)