Arab or Irish-American on QI (5)
I believe the answer is:
iraqi
'arab' is the definition.
(I've seen this before)
'irish-american on qi' is the wordplay.
'irish' becomes 'IR' (abbreviation).
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'on' says to put letters next to each other.
'ir'+'a'+'qi'='IRAQI'
'or' is the link.
(Other definitions for iraqi that I've seen before include "Probably a Muslim" , "Native of Baghdad, say" , "Asian" , "Someone from Baghdad, for example" , "Resident of Baghdad, say" .)