Irish with a question: one for Arab (5)
I believe the answer is:
iraqi
'arab' is the definition.
(I've seen this before)
'irish with a question one' is the wordplay.
'irish' becomes 'IR' (abbreviation for Irish).
'with' says to put letters next to each other.
'question' becomes 'q'.
'one' becomes 'i' (Roman numeral).
'ir'+'a'+'q'+'i'='IRAQI'
'for' acts as a link.
(Other definitions for iraqi that I've seen before include "Native of Baghdad, say" , "Arab national" , "Sadaam, say" , "foreigner" , "Inhabitant of Baghdad?" .)