Learning rising political policy maker on left has advantage (9)
I believe the answer is:
knowledge
'learning' is the definition.
(I've seen this before)
'rising political policy maker on left has advantage' is the wordplay.
'rising' says the letters should be written backwards (going up in a down clue).
'political policy maker' becomes 'wonk' (someone interested in political policy).
'on left' becomes 'l' (common abbreviation. I am not sure about the 'on' bit.).
'has' is a charade indicator (letters next to each other).
'advantage' becomes 'edge' (having the edge is having an advantage).
'wonk' backwards is 'know'.
'know'+'l'+'edge'='KNOWLEDGE'
(Other definitions for knowledge that I've seen before include "A little of it is said to be a dangerous thing" , "Information, learning or enlightenment" , "Information; awareness" , "Awareness - erudition" , "Info" .)