The most common and most likely answer to this crossword clue is the 8 letter word DEFIANCE
I've seen this crossword clue in The Guardian
D
E
F
I
A
N
C
E
More clues leading to the result DEFIANCE
- Opposition of English female I encountered during social occasion
- Rebelliousness of French chap bound for altar?
- Challenging behaviour to get rid of husband-to-be, apparently
- Resistance of French fellow who's engaged
- Provocation of French intended
- Confrontation of French by groom-to-be
- A fence I’d altered leading to opposition
- Temerity of Parisian guy who’s about to join union
- Notes intended to be threatening
- Lower classes intended mutiny
Buddy explains!

The straight part
We know that "mutiny" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case mutiny = defiance.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 DEFIANCE mean?
DEFIANCE noun- The feeling, or spirit of being defiant.
- Open or bold resistance to or disregard for authority, opposition, or power.
- A challenging attitude or behaviour; challenge.