Athenian room at the top (5)
I believe the answer is:
attic
This clue is a double definition.
'athenian' is the first definition.
(I've seen this in another clue)
'room at the top' is the second definition.
(room at the top of a house)
(Other definitions for attic that I've seen before include "Lofty room" , "Small room at the top" , "Upstairs room" , "where high-ups are found?" , "of Greek region" .)