Beginning to scare me about revolutionary's plot (6)
I believe the answer is:
scheme
'plot' is the definition.
(scheming is a kind of plotting)
'beginning to scare me about revolutionary's' is the wordplay.
'beginning to' indicates taking the first letters.
'about' is a charade indicator (letters next to each other).
'revolutionary' becomes 'che' (Che Guevara the Marxist revolutionary**).
The first letter of 'scare' is 's'.
'me' put after 'che' is 'cheme'.
's'+'cheme'='SCHEME'
(Other definitions for scheme that I've seen before include "proposal" , "Plan or act secretly" , "Plan - intrigue" , "Systematic of crafty plan of action" , "Plan, ruse" .)