Human whose body has been taken over by machines (6)
I believe the answer is:
cyborg
'human whose body has been taken over by machines' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for cyborg that I've seen before include "Robot made of biological and machine parts" , "Human whose body has been taken over by machines" , "Sci-fi being with computer implants" , "Person incorporating mechanical elements" , "Human enhanced by mechanical elements" .)