Light switch position (3)
I believe the answer is:
off
'light switch position' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for off that I've seen before include "Of food, begining to decay" , "(Of food) no longer fresh" , "Away, at a distance" , "Away, or no longer on the menu perhaps" , "below par" .)