The most common and most likely answer to this crossword clue is the 3 plus 12 letter word TEN COMMANDMENTS
I've seen this crossword clue in The Times
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More clues leading to the result TEN COMMANDMENTS
- Charge crew under canvas for code on tablets
- Decimal-based code embedded in old tablets
- First ever set of instructions to be handed down?
- X, mark probing new evidence of collision — get the law!
- Religious code of Butterfly State gets guys encamped
- Communication with soldiers in camp conveys orders from above
- Holy orders
- It's 10, and me not having a book starting to see a film
- Number of orders booked many years ago
Buddy explains!
The straight part
We know that "code on tablets" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case code on tablets = ten commandments.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.