Old communist, revolutionary figure on left (5)
I believe the answer is:
lenin
'old communist' is the definition.
'revolutionary figure on left' is the wordplay.
'revolutionary' says the letters should be written in reverse.
'figure' becomes 'nine' (I've seen this in other clues**).
'on' means one lot of letters go next to another.
'left' becomes 'l' (common abbreviation).
'nine'+'l'='ninel'
'ninel' backwards is 'LENIN'.
(Other definitions for lenin that I've seen before include "Vladimir Ilich Ulyanov" , "First leader of USSR" , "Communist leader" , "Marxist theoretician" , "First Soviet leader" .)