Reform vital to a North European (7)
I believe the answer is:
latvian
'north european' is the definition.
(Latvia is in northern Europe)
'reform vital to a' is the wordplay.
'reform' indicates an anagram (letters in a new form).
'to a' becomes 'an'.
'vital' anagrammed gives 'latvi'.
'latvi'+'an'='LATVIAN'
(Other definitions for latvian that I've seen before include "One from Riga" , "European national" , "who lives in ex-Communist country?" , "Baltic language" , "republican" .)