Greek character leading small rebellion (6)
I believe the answer is:
Here is my best explanation:
'rebellion' is the definition.
(mutiny is a kind of rebellion)
'greek character leading small' is the subsidiary indication.
'greek character' becomes 'mu' (**).
'leading' says to put letters next to each other.
'small' becomes 'tiny' ('tiny' can be similar in meaning to 'small').
(Other definitions for mutiny that I've seen before include "Open rebellion by sailors or soldiers", "Armed forces rebellion", "Insurrection", "Open rebellion against constituted authority", "Military rebellion", "Rebellion as on Bligh's Bounty", "revolt", "Rebellion in the armed forces", "Revolt against authority" and "Rising, rebellion".)