The most common and most likely answer to this crossword clue is the 9 letter word LINEATION
L
I
N
E
A
T
I
O
N
Buddy explains!
The straight part
We know that "Orderly arrangement" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case orderly arrangement = lineation.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 LINEATION mean?
LINEATION noun- A linear feature in rock, often structural
- The way in which line breaks are inserted in a poem