Unused, inactive (4)
I believe the answer is:
idle
I believe this clue is a double definition.
'unused' is the first definition.
(I know that unused can be written as idle)
'inactive' is the second definition.
(similar in meaning)
(Other definitions for idle that I've seen before include "Turn over" , "Without work" , "Unoccupied or not in use" , "Not occupied" , "Hang about doing nothing" .)