Break away from some predecessors, being revolutionary (6)
I believe the answer is:
secede
'break away' is the definition.
(I know that break away can be written as secede)
'from some predecessors being revolutionary' is the wordplay.
'from' indicates a hidden word.
'being revolutionary' says the letters should be written in reverse (letters revolve around).
'edeces' is hidden in the letters of 'some predecessors'.
'edeces' written backwards gives 'SECEDE'.
(Other definitions for secede that I've seen before include "Formally withdraw (from federal union)" , "leave union" , "Withdraw (from a federal union or organisation)" , "Withdraw (politically)" , "Withdraw formally from membership of an organisation" .)