Fulminating in a bad way, Republican takes lead (7)
I believe the answer is:
railing
'fulminating' is the definition.
(both can mean protesting or raging against)
'in a bad way republican takes lead' is the wordplay.
'in a bad way' becomes 'ailing' (somebody who is ailing is unwell).
'republican' becomes 'r' (abbreviation).
'takes lead' means one lot of letters go next to another (to take the lead can mean to go in front of).
'ailing' after 'r' is 'RAILING'.
(Other definitions for railing that I've seen before include "Complaining - fence" , "Haranguing -- horizontal bar on supports" , "Noisily protesting" , "Fencing - rating" , "Metal barrier" .)