Announced changes of course on crime sentencing rules (6)
I believe the answer is:
syntax
'sentencing rules' is the definition.
(rules for writing sentences or clauses)
I don't understand how the remainder of the clue works.
(Other definitions for syntax that I've seen before include "Grammatical rules" , "Grammatical construction" , "The rules governing the arrangement of words in sentences etc" , "Arrangement of words and phrases in a sentence" , "Rules governing formation of sentences and phrases" .)