The most common and most likely answer to this crossword clue is the 9 letter word RIFF-RAFF
R
I
F
F
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R
A
F
F
Buddy explains!
The straight part
We know that "Rabble" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case rabble = riff-raff.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 RIFF-RAFF mean?
RIFF-RAFF noun- The rabble; crowds; the common people.
- Sweepings; refuse.