The most common and most likely answer to this crossword clue is the 5 letter word FATWA
I've seen this crossword clue in The Times
F
A
T
W
A
More clues leading to the result FATWA
- Ruling dripping with mendacity at heart
- Thick roll of banknotes curtailed religious judgment
- Overweight women given a death sentence
- Decree carrying a lot of weight with American
- Large wife served with a religious decree
- Judicial decision, mostly deadly when woman’s involved
- Female in conflict ignoring right judgment
- Religious ruling defended by chief at Walsingham
- Ayatollah’s given it a bit of a twang
- Substantial weight put on a religious ruling
Buddy explains!

The straight part
We know that "Ruling" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case ruling = fatwa.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 FATWA mean?
FATWA noun- A legal opinion, decree or ruling issued by a mufti or other Islamic lawyer.
- To make somebody the subject of a fatwa, especially a ban or death sentence.