Office problem raised with each unionist (6)
I believe the answer is:
bureau
'office' is the definition.
('bureau' can be a synonym of 'office')
'problem raised with each unionist' is the wordplay.
'problem' becomes 'rub' (**).
'raised' says the letters should be written in reverse.
'with' is a charade indicator (letters next to each other).
'each' becomes 'ea'.
'unionist' becomes 'u' (abbreviation as in Democratic Unionist Party).
'rub' in reverse letter order is 'bur'.
'bur'+'ea'+'u'='BUREAU'
(Other definitions for bureau that I've seen before include "Foreign office" , "Chest of drawers or office" , "Agency - writing desk" , "Office; writing desk" , "Room" .)