Arab is soon to return (5)
I believe the answer is:
omani
'arab' is the definition.
(someone from Oman)
'soon to return' is the wordplay.
'soon' becomes 'in a mo' (in a mo).
'to return' says the letters should be written in reverse.
'inamo' back-to-front is 'OMANI'.
'is' acts as a link.
(Other definitions for omani that I've seen before include "Middle East national" , "M East person" , "Native of one Arabian sultanate" , "Eg, a native of Muscat" , "Gulf Arab" .)