Use a second time in the previous graph (7)
I believe the answer is:
exploit
'use' is the definition.
(I know that use is a more specific form of the action exploit)
'a second time in the previous graph' is the wordplay.
'a second time' becomes 'i' (2nd letter of 'time').
'in the' indicates putting letters inside.
'previous' becomes 'ex' (prefix meaning former or onetime).
'graph' becomes 'plot' (I've seen this in another clue).
'ex'+'plot'='explot'
'i' placed inside 'explot' is 'EXPLOIT'.
(Other definitions for exploit that I've seen before include "Bunk" , "Heroic deed" , "Fleece?" , "The deed to make gain from" , "Take advantage of escapade?" .)