Office or agency (6)
I believe the answer is:
bureau
I believe this clue is a double definition.
'office' is the first definition.
(synonyms)
'agency' is the second definition.
(synonyms)
'or' acts as a link.
(Other definitions for bureau that I've seen before include "Foreign office" , "The ------, familiar name of the FBI" , "Wtiting desk" , "The B in the FBI" , "Item of furniture" .)