Bright visitors arrive by backstreet (6)
I believe the answer is:
comets
'bright visitors' is the definition.
Although both the answer and definition are plural nouns, I don't understand how they can define each other.
'arrive by backstreet' is the wordplay.
'arrive' becomes 'come' (coming is a kind of arriving).
'by' says to put letters next to each other.
'backstreet' becomes 'ts' ('st' backwards).
'come'+'ts'='COMETS'
Can you help me to learn more?
(Other definitions for comets that I've seen before include "Space travellers" , "Heavenly bodies with tails" , "Small extraterrestrial bodies" .)