Said Python is a graven image (4)
I believe the answer is:
idol
'a graven image' is the definition.
('idol' can be a synonym of 'graven image')
'said python' is the wordplay.
'said' shows a homophone (sound like).
'python' becomes 'idle' (Monty Python member Eric Idle).
'idle' sounds like 'IDOL'.
'is' is the link.
(Other definitions for idol that I've seen before include "loved one" , "Worshipped figure (not painting); revered person" , "Hero of screen or stage" , "Object of excessive love or devotion" , "A graven image or object of adoration" .)