Toppled tyrant ultimately disgraced, beheaded (7)
I believe the answer is:
tumbled
'toppled' is the definition.
('tumble' can be a synonym of 'topple')
'tyrant ultimately disgraced beheaded' is the wordplay.
'ultimately' says to take the final letters.
'disgraced' becomes 'humbled' (disgrace can mean to humble or demean).
'beheaded' means to remove the first letter (the head of the word is removed).
The final letter of 'tyrant' is 't'.
'humbled' with its initial letter taken off is 'umbled'.
't'+'umbled'='TUMBLED'
(Other definitions for tumbled that I've seen before include "Tripped" , "Fell rapidly" , "Toppled, fell to the ground" , "Fell and rolled over" .)