Skylit lobbies (5)
I believe the answer is:
atria
'skylit lobbies' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for atria that I've seen before include "Central areas in buildings; open to the sky" , "Upper chambers of the heart" , "Open-roofed courts" , "Parts of the heart or of Roman houses" , "Central courts, halls" .)