Tool used for law-breaking (3)
I believe the answer is:
awl
'tool' is the definition.
(awl is a kind of tool)
'law-breaking' is the wordplay.
'breaking' indicates an anagram.
'law' with letters rearranged gives 'AWL'.
'used for' is the link.
(Other definitions for awl that I've seen before include "Cobbler's tool" , "Shoemaker's tool" , "Using sharp tool" , "may bore" , "Boring tool sounds comprehensive" .)