Across a thoroughfare, travel (7)
I believe the answer is:
astride
'across' is the definition.
(thesaurus)
'a thoroughfare travel' is the wordplay.
'thoroughfare' becomes 'st' (I've seen this in other clues).
'travel' becomes 'ride' (riding is a kind of travelling).
'a'+'st'+'ride'='ASTRIDE'
(Other definitions for astride that I've seen before include "Not side saddle" , "Straddling (horse)" , "Extending across" , "With feet apart" , "With one leg on either side, as sitting on horse" .)