Ness attack after Untouchables' last patsy (9)
I believe the answer is:
scapegoat
'patsy' is the definition.
(I've seen this in another clue)
'ness attack after untouchables' last' is the wordplay.
'ness' becomes 'cape' (synonyms).
'attack' becomes 'go at' (go at).
'after' means one lot of letters go next to another.
'last' indicates one should take the final letters.
The final letter of 'untouchables' is 's'.
'cape'+'goat'='capegoat'
'capegoat' after 's' is 'SCAPEGOAT'.
(Other definitions for scapegoat that I've seen before include "Patsy" , "One given the blame" , "One blamed for others' mistakes" , "One who takes the blame for others" , "Can carrier" .)