Exploited? That’s not new (4)
I believe the answer is:
used
I believe this clue is a double definition.
'exploited?' is the first definition.
(exploiting is a kind of using)
'not new' is the second definition.
(thesaurus)
'that's' is the link.
(Other definitions for used that I've seen before include "Brought into play" , "Previously owned by another" , "Manipulated American editor" , "with some traffic" , "Employed - exploited" .)