Tsar following dictator killing off a popular composer (8)
I believe the answer is:
sullivan
'popular composer' is the definition.
'Sullivan' can be an answer for 'composer' (Sullivan is an example). I am not sure about the 'popular' bit.
'tsar following dictator killing off a' is the wordplay.
'tsar' becomes 'ivan' (name of several Russian tsars).
'following' says to put letters next to each other.
'dictator' becomes 'Sulla' (Roman dictator).
'killing off' suggests deleting specific letters.
'sulla' with 'a' taken away is 'sull'.
'ivan' put after 'sull' is 'SULLIVAN'.
Can you help me to learn more?
(Other definitions for sullivan that I've seen before include "The S in G&S" , "Composer of music for Ruddigore, d. 1900" , "The Lost Chord composer" , "Savoy Opera composer" , "Mikado composer" .)