Use badly and prosecute (3)
I believe the answer is:
sue
'prosecute' is the definition.
(thesaurus)
'use badly' is the wordplay.
'badly' is an anagram indicator.
'use' is an anagram of 'SUE'.
'and' acts as a link.
(Other definitions for sue that I've seen before include "The girl to take to court" , "Susan (dim.)" , "Litigious girl" , "Use to take to court" , "Take case against in court" .)