Best section of thoroughfare, lit extensively (5)
I believe the answer is:
elite
'best' is the definition.
(elite can mean the very best of a group)
'section of thoroughfare lit extensively' is the wordplay.
'section of' says the answer is hidden in the clue.
'ELITE' is hidden within 'thoroughfare lit extensively'.
(Other definitions for elite that I've seen before include "Choice; best" , "Top group f" , "Selected as the best" , "one of the letter sizes" , "Group considered to have superior status" .)