Published one in The Scotsman and a national (7)
I believe the answer is:
iranian
'a national' is the definition.
(I know this)
'published one in the scotsman' is the wordplay.
'published' becomes 'ran' (running is a kind of publishing).
'one' becomes 'i' (Roman numeral).
'in the' indicates putting letters inside.
'scotsman' becomes 'ian' (common Scottish name).
'ran'+'i'='rani'
'rani' put within 'ian' is 'IRANIAN'.
'and' is the link.
(Other definitions for iranian that I've seen before include "foreigner" , "Foreign national" , "from the Middle East" , "One from Isfahan" , "One from Tehran, say" .)