Revolutionary number left heading west (5)
I believe the answer is:
lenin
'revolutionary' is the definition.
(I've seen this before)
'number left heading west' is the wordplay.
'number' becomes 'nine' (nine is a kind of number).
'left' becomes 'l' (common abbreviation).
'heading west' shows that the letters should be reversed in order.
'nine'+'l'='ninel'
'ninel' reversed gives 'LENIN'.
(Other definitions for lenin that I've seen before include "Soviet Union's first premier" , "Vladimir Ilyich Ulyanov, d. 1924" , "First Soviet leader" , "Vladimir Ilich Ulyanov" , "Linen for Communist" .)