Wander off, turning on the light (5)
I believe the answer is:
stray
This clue could be a double definition.
'wander off' is the first definition.
(I've seen this before)
'turning on the light' is the second definition.
'stray' can be an answer for 'turning' (thesaurus). I'm unsure of the 'on the light' bit.
Can you help me to learn more?
(Other definitions for stray that I've seen before include "Vagrant" , "Deviate" , "out of place" , "Drift - isolated" , "Depart from the right path" .)