The most common and most likely answer to this crossword clue is the 5 letter word REBEL
I've seen this crossword clue in The Times
R
E
B
E
L
More clues leading to the result REBEL
- Where belief conceals dissent
- Bishop in spin as one who defies convention?
- Initially breezy wind is about to rise
- Nonconformist putting bishop into spin
- Revolutionary to stagger around leader of Bolsheviks
- Rise about start of breakfast — odd bits of meal missed
- Insurgent put base of bomb in rock
- Revolutionary Bishop enthralled by rock
- Frothy beer left to rise
- Rise in temperature believable
Buddy explains!

The straight part
We know that "Revolutionary" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case revolutionary = rebel.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 REBEL mean?
REBEL noun- A person who resists an established authority, often violently
- A person from the Confederate States of America
- To resist or become defiant toward an authority.