A student just under ten turned red (5)
I believe the answer is:
lenin
'red' is the definition.
(Vladimir Lenin, Russian communist or 'red')
'a student just under ten turned' is the wordplay.
'a student' becomes 'l' (as in L-plates for learner drivers).
'just under ten' becomes 'nine' (I can't explain this - if you can you should give a lot more credence to this answer).
'turned' says the letters should be written backwards.
'nine' in reverse letter order is 'enin'.
'l'+'enin'='LENIN'
Can you help me to learn more?
(Other definitions for lenin that I've seen before include "Soviet Union's first premier" , "Vladimir Ilyich Ulyanov, d. 1924" , "Linen for Communist" , "Vladimir Ilich Ulyanov" , "Marxist theoretician" .)