Rain irritated Scotsman and this national (7)
I believe the answer is:
iranian
'this national' is the definition.
The answer and definition can be both people as well as being singular nouns.
Maybe there's a link between them I don't understand?
'rain irritated scotsman' is the wordplay.
'irritated' indicates anagramming the letters (I've seen this in other clues).
'scotsman' becomes 'ian' (common Scottish name).
'rain' is an anagram of 'iran'.
'iran'+'ian'='IRANIAN'
'and' acts as a link.
Can you help me to learn more?
(Other definitions for iranian that I've seen before include "Native of modern Persia" , "Nationality of citizen of Tehran" , "Tehran native, say" , "One from Isfahan" , "From Tehran, perhaps?" .)