... lights, aurora borealis (8)
I believe the answer is:
I believe this clue is a double definition.
'lights' is the first definition.
(I've seen this before)
'aurora borealis' is the second definition.
(I've seen this before)
(Other definitions for northern that I've seen before include "Coming from areas closer to the Arctic" , "Coming from boreal parts" , "Relating to Belfast, say" , "- Ireland; - lights" , "Part of the UK" .)