Livid having been beaten badly (5,3,4)
I believe the answer is:
black and blue
'livid' is the definition.
(I know that livid can be written as black-and-blue)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for black and blue that I've seen before include "two balls at snooker" , "Twice shaded" , "Discoloured, as from a bruise" , "looking thoroughly beaten?" , "Badly bruised" .)