The most common and most likely answer to this crossword clue is the 6 letter word SYNTAX
I've seen this crossword clue in The Daily Telegraph
S
Y
N
T
A
X
More clues leading to the result SYNTAX
- Announced changes of course on crime sentencing rules
- Structure of speech announcing duty on beer and fags?
- Arrangement with cheap horn for Spooner
- Correct grammar which is wrong – they say it’s a duty
- Wrong points announced in speech outlining grammatical structure
- Set of rules? Something bad, reportedly a burden
- Announced wrong charge for structure of sentence?
- Duty to chase wrong-sounding grammatical structure
- Government income from evil-sounding sentence structure?
- Finishing touches for scripts by Dan Levy, showing correct use of language
Buddy explains!

The straight part
We know that "sentencing rules" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sentencing rules = syntax.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does SYNTAX mean?
SYNTAX noun- A set of rules that govern how words are combined to form phrases and sentences.
- The formal rules of formulating the statements of a computer language.
- The study of the structure of phrases, sentences and language.