Greek hero’s body is as Zeus decapitated (8)
I believe the answer is:
odysseus
'greek hero's' is the definition.
(I've seen this before)
I can't explain the rest of the clue.
(Other definitions for odysseus that I've seen before include "Homer's wandering hero" , "Homeric hero" , "Greek hero of an epic journey home from Troy" , "Gr. hero, aka Ulysses" , "Homeric wanderer" .)