Execute badly (5)
I believe the answer is:
lynch
'execute' is the definition.
(thesaurus)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for lynch that I've seen before include "String up illegally" , "Punish without trial" , "Judge and execute without the law" , "Kill without legal sanction" , "- - law (= mob violence)" .)