Old Ottoman guide, a bore, going to a sultanate in Arabia (8)
I believe the answer is:
dragoman
'old ottoman guide' is the definition.
(historical term for a Turkish interpreter )
'a bore going to a sultanate in arabia' is the wordplay.
'a bore' becomes 'drag' (I've seen this before).
'going to' says to put letters next to each other.
'a sultanate in arabia' becomes 'oman' (Middle Eastern country).
'drag'+'oman'='DRAGOMAN'
(Other definitions for dragoman that I've seen before include "Guide" , "Eastern interpreter" .)