Rabble rose and got toffs abruptly guillotined initially (6)
I believe the answer is:
ragtag
'rabble' is the definition.
('ragtag' can be a synonym of 'rabble')
'rose and got toffs abruptly guillotined initially' is the wordplay.
'initially' indicates taking the first letters.
The initial letters of 'rose and got toffs abruptly guillotined' is 'RAGTAG'.
(Other definitions for ragtag that I've seen before include "hoi polloi" , "Untidy, disorganised" , "Disparaging term for the common people" , "Incongruously varied in character" , "Masses" .)