A minor route overseas (6)
I believe the answer is:
abroad
'overseas' is the definition.
(synonyms)
'a minor route' is the wordplay.
'minor route' becomes 'b road' (B-road).
'a'+'broad'='ABROAD'
(Other definitions for abroad that I've seen before include "to France, maybe" , "Europe, for example" , "Stare lecherously at (someone)" , "out of UK?" , "Pole would be so" .)