The most common and most likely answer to this crossword clue is the 11 letter word CHEERLEADER
I've seen this crossword clue in The Daily Telegraph
C
H
E
E
R
L
E
A
D
E
R
More clues leading to the result CHEERLEADER
- Support director here and declare for new distribution
- Assertive supporter's revolutionary songs heard by Queen
- Supporters of Queen captured by revolutionary chiefs
- Church always wanting newspaper article? I’ll drum up support
- Revolutionary, 20, adopting line ‘I’m in charge of support!’
- During the game, she’s no reserve!
Buddy explains!

The straight part
We know that "Supporters" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case supporters = cheerleader.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 CHEERLEADER mean?
CHEERLEADER noun- A person, usually a young, attractive female, who encourages applause and cheers at a sports event, and wearing a specially-designed uniform in the official colors of the team he/she cheers for.
- A person who rallies support for any cause.