Antechamber (5)
I believe the answer is:
lobby
'antechamber' is the definition.
(I know that antechamber can be written as lobby)
This is all the clue.
(Other definitions for lobby that I've seen before include "Foyer" , "Entrance room" , "Antechamber" , "Seek to influence (a legislator)" , "Entrance hall - seek to influence" .)