Exploited the old (4)
I believe the answer is:
used
I believe this is a double definition.
'exploited' is the first definition.
('used' can be a synonym of 'exploited')
'the old' is the second definition.
(I've seen this before)
(Other definitions for used that I've seen before include "with some traffic" , "Not fresh" , "Scottish expert" , "like majority of cars?" , "Exploited group" .)