Chivalrous knight throttling one former leader (5)
I believe the answer is:
boris
'one former leader' is the definition.
The definition suggests a singular noun which matches the answer.
'chivalrous knight throttling' is the wordplay.
'chivalrous' becomes 'i' (I am not sure about this - if you are sure you should believe this answer much more).
'knight' becomes 'Bors' (Arthurian knight).
'throttling' means one lot of letters goes inside another.
'i' put inside 'bors' is 'BORIS'.
Can you help me to learn more?
(Other definitions for boris that I've seen before include "- Godunov, Mussorgsky opera" , "- Johnson, Mayor of London" , "- Godunov, Russian tsar" , "Russian name" , "-- Godunov; -- Johnson" .)