Greek character leads 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 leads small' is the subsidiary indication.
'greek character' becomes 'mu' (**).
'leads' means one lot of letters go next to another.
'small' becomes 'tiny' ('tiny' can be similar in meaning to 'small').
(Other definitions for mutiny that I've seen before include "Open rebellion against constituted authority", "Rising, rebellion", "Insurrection", "Armed forces rebellion", "revolt", "Military rebellion", "Revolt against authority", "Rebellion by sailors or soldiers", "Rebellion as on Bligh's Bounty" and "Rebellion in the armed forces".)