Fool in show of enjoyment backed rebellion (6)
I believe the answer is:
mutiny
'rebellion' is the definition.
(I know that mutiny is a type of rebellion)
'fool in show of enjoyment backed' is the wordplay.
'fool' becomes 'nit' (both can mean a stupid person).
'in' means one lot of letters goes inside another.
'show of enjoyment' becomes 'yum' (yum expresses enjoyment of food).
'backed' says the letters should be written in reverse.
'nit' placed within 'yum' is 'ynitum'.
'ynitum' in reverse letter order is 'MUTINY'.
(Other definitions for mutiny that I've seen before include "Insurrection" , "Open rebellion by sailors or soldiers" , "Rising, rebellion" , "Revolt against authority" , "Open rebellion against constituted authority" .)