Contradiction’s genuine about object of ridicule (8)
I believe the answer is:
rebuttal
'contradiction's' is the definition.
(thesaurus)
'genuine about object of ridicule' is the wordplay.
'genuine' becomes 'real' ('real' is associated in meaning with 'genuine').
'about' is an insertion indicator.
'object of ridicule' becomes 'butt' (I've seen this before).
'real' going around 'butt' is 'REBUTTAL'.
(Other definitions for rebuttal that I've seen before include "A disproving or rejection of evidence" , "statement delivered to counter" , "reply to accusation" , "resistance to attack" , "arguing to the contrary" .)