Arab resident soon upset (5)
I believe the answer is:
omani
'arab' is the definition.
(someone from Oman)
'soon upset' is the wordplay.
'soon' becomes 'in a mo' (in a mo).
'upset' says the letters should be written backwards.
'inamo' back-to-front is 'OMANI'.
'resident' acts as a link.
This may not be correct. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for omani that I've seen before include "From an Arabian country, capital Muscat" , "One from Muscat" , "coming from the Middle East" , "Asian" , "Someone from Muscat" .)