Post office (7)
I believe the answer is:
station
I believe this clue is a double definition.
'post' is the first definition.
('station' can be a synonym of 'post')
'office' is the second definition.
(thesaurus)
(Other definitions for station that I've seen before include "Train stop" , "Train halt" , "Headquarters" , "camp?" , "Base, post" .)