Married chum's brought into Middle East location as investigator (9)
I believe the answer is:
ombudsman
'investigator' is the definition.
(ombudsman is a kind of investigator)
'married chum's brought into middle east location' is the wordplay.
'married' becomes 'm'.
'chum's' becomes 'bud's' (both can mean a friend).
'brought into' indicates putting letters inside.
'middle east location' becomes 'Oman' (Middle Eastern country).
'm'+'buds'='mbuds'
'mbuds' going into 'oman' is 'OMBUDSMAN'.
'as' is the link.
(Other definitions for ombudsman that I've seen before include "Official pursuing complaints against government departments" , "Government appointee who investigates complaints" , "Parliamentary commissioner" , "Commissioner investigating complaints by the public" , "Commisioner" .)