Torment resulting from unsympathetic law? Do a mischief! (4,3,3,5,4)
I believe the answer is:
play cat and mouse with
Here is my best explanation:
'torment' is the definition.
'unsympathetic law? do a mischief' is the wordplay.
'mischief' is an anagram indicator.
'unsympatheticlawdoa' is an anagram of 'playcatandmousewith'.
'resulting from' is the link.