Arab shortly coming over (5)
I believe the answer is:
omani
'arab' is the definition.
(someone from Oman)
'shortly coming over' is the wordplay.
'shortly' becomes 'in a mo' (I've seen this before).
'coming over' shows that the letters should be reversed in order.
'inamo' in reverse letter order is 'OMANI'.
(Other definitions for omani that I've seen before include "Eg, a native of Muscat" , "Gulf native" , "One from Muscat" , "Inhabitant of Middle Eastern sultanate" , "Middle East national" .)