The most common and most likely answer to this crossword clue is the 9 letter word CODIFYING
I've seen this crossword clue in Financial Times
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More clues leading to the result CODIFYING
Buddy explains!

The straight part
We know that "arranger’s job?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case arranger’s job? = codifying.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 CODIFYING mean?
CODIFYING verb- To reduce to a code, to arrange into a code.
- To collect and arrange in a systematic form.
- A codification.