March miles with figure backing political doctrine (7)
I believe the answer is:
marxism
'political doctrine' is the definition.
(I've seen this before)
'march miles with figure backing' is the wordplay.
'march' becomes 'Mar' (abbreviation).
'miles' becomes 'm' (common abbreviation).
'with' is a charade indicator (letters next to each other).
'figure' becomes 'six' (six is a number).
'backing' says the letters should be written in reverse.
'six' written backwards gives 'xis'.
'm' after 'xis' is 'xism'.
'mar'+'xism'='MARXISM'
(Other definitions for marxism that I've seen before include "Left-wing ideology" , "political theory" , "Left-wing system" , "Basis of communism" , "Communist belief" .)