The most common and most likely answer to this crossword clue is the 9 letter word PELL-MELL
I've seen this crossword clue in Financial Times
P
E
L
L
-
M
E
L
L
More clues leading to the result PELL-MELL
- Disorder in London thoroughfare, ending in trouble for area repeatedly
- Hand-to hand fight on helter- skelter
- Impetuously supplying rhymes for 21?
- Measure introduced by prime minister, that measure creating disorder
- Politician adopts measures recklessly
- The plimsoll line crossed? In this ocean, tricky to be unloaded at full tilt
- Confusedly, game once having Europeans replacing Americans
Buddy explains!

The straight part
We know that "disorder" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case disorder = pell-mell.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 PELL-MELL mean?
PELL-MELL noun- A 17th-century game in which a ball was driven along an alley and through a hoop using a mallet.
- Hasty and uncontrolled.
- In haste and chaos; uncontrolledly, confusedly.