Minor thoroughfares with a lot of theatres (8)
I believe the answer is:
broadway
'a lot of theatres' is the definition.
I don't understand the remainder of the clue.
(Other definitions for broadway that I've seen before include "that took in Chicago and Oklahoma!" , "Cotswold village" , "New York Theaterland" , "A bow yard for New York theatre" , "Manhattan street" .)