Maim fellow by breaking leg (6)
I believe the answer is:
mangle
'maim' is the definition.
(thesaurus)
'fellow by breaking leg' is the wordplay.
'fellow' becomes 'man' (fellow can mean a man).
'by' is a charade indicator (letters next to each other).
'breaking' indicates an anagram.
'leg' is an anagram of 'gle'.
'man'+'gle'='MANGLE'
(Other definitions for mangle that I've seen before include "Old-fashioned laundry appliance" , "Clothes-wringer for leg-man" , "Ruin" , "Mutilate badly; wringer" , "rolling-press" .)