The most common and most likely answer to this crossword clue is the 7 letter word STATUTE
I've seen this crossword clue in Financial Times
S
T
A
T
U
T
E
More clues leading to the result STATUTE
- Law in country restricting trade union
- Condition endlessly applied to limits of the law
- Giant finally caught by David, say — that’s the law
- First of trains passing through Monument as a rule
- Something set in stone around government, ultimately, as a rule
- Figure includes Newton’s fourth law
- Act to get figure with a modicum of truth in it
- Law taking time to stop representation
- Act of sovereign country occupied by junta intermittently
- Proper time in part of US for law
Buddy explains!

The straight part
We know that "Law" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case law = statute.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 STATUTE mean?
STATUTE noun- Written law, as laid down by the legislature.
- (common law) Legislated rule of society which has been given the force of law by those it governs.