Old male, one from Muscat, say? (5)
I believe the answer is:
omani
'from muscat say?' is the definition.
(I've seen this in another clue)
'old male one' is the wordplay.
'old' becomes 'o' (abbreviation).
'male' becomes 'man' (man is a kind of male).
'one' becomes 'i' (Roman numeral).
'o'+'man'+'i'='OMANI'
(Other definitions for omani that I've seen before include "One from Muscat" , "Middle East national" , "From an Arabian country, capital Muscat" , "Gulf native" , "one from the Middle East" .)