Best stretch of thoroughfare, lit extensively (5)
I believe the answer is:
elite
'best' is the definition.
(elite can mean the very best of a group)
'stretch of thoroughfare lit extensively' is the wordplay.
'stretch of' indicates a hidden word (a stretch of letters from the clue).
'ELITE' is hidden within 'thoroughfare lit extensively'.
(Other definitions for elite that I've seen before include "Superior group in society" , "Superior or favoured group of people" , "Chosen ones" , "Exclusive group" , "Select part" .)