The most common and most likely answer to this crossword clue is the 5 plus 4 letter word SALLY ARMY
I've seen this crossword clue in Independent
S
A
L
L
Y
A
R
M
Y
More clues leading to the result SALLY ARMY
Buddy explains!
The straight part
We know that "who aim to spread the word?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case who aim to spread the word? = sally army.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.