Street light to go off (5)
I believe the answer is:
stray
'go off' is the definition.
(I've seen this in another clue)
'street light' is the wordplay.
'street' becomes 'st' (abbreviation).
'light' becomes 'ray' (ray is a kind of light).
'st'+'ray'='STRAY'
'to' is the link.
(Other definitions for stray that I've seen before include "Deviate" , "Waif and - -" , "Drift - isolated" , "Vagrant" , "Lost pet" .)