The most common and most likely answer to this crossword clue is the 9 letter word SHOOT-OUT
I've seen this crossword clue in The Guardian
S
H
O
O
T
-
O
U
T
More clues leading to the result SHOOT-OUT
Buddy explains!
The straight part
We know that "deciding procedure" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case deciding procedure = shoot-out.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 SHOOT-OUT mean?
SHOOT-OUT noun- A decisive battle, especially a gunfight.
- A penalty shootout.
- A series of penalty shots during which a tied game is resolved.
- A multitable poker tournament in which only the last player on a table goes on to the next.