Bold to participate in revolt, seizing power (12)
I believe the answer is:
enterprising
'bold' is the definition.
('enterprising' can be similar in meaning to 'bold')
'participate in revolt seizing power' is the wordplay.
'participate' becomes 'enter' ('enter' can be a synonym of 'participate').
'in revolt' becomes 'rising'.
'seizing' is an insertion indicator.
'power' becomes 'p'.
'enter'+'rising'='enterrising'
'enterrising' placed around 'p' is 'ENTERPRISING'.
'to' is the link.
(Other definitions for enterprising that I've seen before include "Adventurous and imaginative" , "Go ahead" , "daring" , "Showing initiative" , "Venturesome" .)