Denial of victim in valid case (8)
I believe the answer is:
rebuttal
'denial' is the definition.
(I've seen this before)
'victim in valid case' is the wordplay.
'victim' becomes 'butt' (butt is a kind of victim).
'in' is an insertion indicator.
'valid case' becomes 'real' (I can't justify this - if you can you should give a lot more credence to this answer).
'butt' going into 'real' is 'REBUTTAL'.
'of' acts as a link.
Can you help me to learn more?
(Other definitions for rebuttal that I've seen before include "arguing to the contrary" , "Denial" , "counterclaim" , "Disproof" , "resistance to attack" .)