Butcher's ultimate ruin? (8)
I believe the answer is:
mutilate
'butcher's' is the definition.
(I've seen this before)
'ultimate ruin?' is the wordplay.
'ruin?' indicates anagramming the letters (I've seen 'ruin' mean this).
'ultimate' with letters rearranged gives 'MUTILATE'.
(Other definitions for mutilate that I've seen before include "Disarm perhaps" , "Damage beyond recognition" , "Injure severely" , "Damage very seriously" , "'Maim, mangle (8)'" .)