Lover seen outside old city office (6)
I believe the answer is:
bureau
'office' is the definition.
(synonyms)
'lover seen outside old city' is the wordplay.
'lover' becomes 'beau' (beau is a kind of lover).
'seen outside' is an insertion indicator.
'old city' becomes 'ur' (ancient city state).
'beau' placed around 'ur' is 'BUREAU'.
(Other definitions for bureau that I've seen before include "Foreign office" , "Piece of furniture with drawers" , "Government department, agency" , "Writing desk with drawers" , "Ancient chipped flint" .)