Law read that changes unfair treatment (3,4)
I believe the answer is:
raw deal
'unfair treatment' is the definition.
(I've seen this before)
'law read that changes' is the wordplay.
'that changes' is an anagram indicator.
'law'+'read'='lawread'
'lawread' is an anagram of 'RAW DEAL'.
(Other definitions for raw deal that I've seen before include "Unfair treatment for unprocessed timber" , "Rough end" , "It's unfair treatment if you get one" , "Unjust payoff" , "Unjust arrangement" .)