Terribly valiant Northern European (7)
I believe the answer is:
latvian
'northern european' is the definition.
'latvian' can be an answer for 'european' (someone from Latvia). I'm unsure of the 'northern' bit.
'terribly valiant' is the wordplay.
'terribly' indicates an anagram.
'valiant' with letters rearranged gives 'LATVIAN'.
Can you help me to learn more?
(Other definitions for latvian that I've seen before include "like rider on tiger" , "One from Riga" , "European national" , "republican" , "From one of the Baltic states" .)