Red, cardinal colour's third from the right (5)
I believe the answer is:
lenin
'red' is the definition.
The answer and definition can be both people as well as being singular nouns.
Perhaps you can see an association between them that I don't see?
'cardinal colour's third from the right' is the wordplay.
'cardinal' becomes 'nine' (a cardinal number).
'colour's third' becomes 'l' (3rd letter of 'colour').
'from the right' shows that the letters should be reversed in order.
'nine'+'l'='ninel'
'ninel' backwards is 'LENIN'.
Can you help me to learn more?
(Other definitions for lenin that I've seen before include "First Soviet leader" , "Head of the Communist state after the fall of the Tsar" , "Marxist theoretician" , "Vladimir Ilich Ulyanov" , "Revolutionary leader" .)