Arabian resident in the Home Nations backed Rishi's conclusion over hiatus (7)
I believe the answer is:
kuwaiti
'arabian' is the definition.
The answer and definition can be both people as well as being singular nouns.
Perhaps you can see an association between them that I can't see?
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for kuwaiti that I've seen before include "Arab" , "From an Eastern Arabian country" , "Gulf state citizen" , "Native of a Gulf state" .)