The most common and most likely answer to this crossword clue is the 6 letter word ULTRAS
U
L
T
R
A
S
Buddy explains!
The straight part
We know that "Those on the fringes" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case those on the fringes = ultras.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 ULTRAS mean?
ULTRAS noun- An ultraroyalist in France.
- An extremist, especially an ultranationalist.
- An especially devoted football fan, typically associated with the intimidating use of extremist slogans, pyrotechnics and sometimes hooligan violence.
- An ultramarathon.
- An ultra-prominent peak.
- (usually capitalised) Code name used by British codebreakers during World War 2 for decrypted information gained from the enemy.