A minor thoroughfare, not in this country (6)
I believe the answer is:
abroad
'not in this country' is the definition.
Both the answer and definition are adjectives. Maybe they are linked in a way I don't understand?
'a minor thoroughfare' is the wordplay.
'minor thoroughfare' becomes 'B road' (B road).
'a'+'broad'='ABROAD'
Can you help me to learn more?
(Other definitions for abroad that I've seen before include "in the field" , "Overseas; (of rumour) widely current" , "In another country, not at home" , "In a foreign country" , "to France, maybe" .)