Left-wing teacher, one with ginger hair (7)
I believe the answer is:
redhead
'one with ginger hair' is the definition.
'left-wing teacher' is the wordplay.
'left wing' becomes 'red' (I've seen this in other clues).
'teacher' becomes 'head'.
'red'+'head'='REDHEAD'
(Other definitions for redhead that I've seen before include "Auburn-haired person" , "Person with rufous hair" , "Person with distinctive coloured hair" , "Ginger nut?" , "Blue Australian" .)