Figure climbing cuts heel, which is red (8)
I believe the answer is:
leninist
'is red' is the definition.
(I've seen this before)
'figure climbing cuts heel' is the wordplay.
'figure' becomes 'nine' (a number of figure).
'climbing' says the letters should be written in reverse (in a down clue, letters climb up).
'cuts' indicates putting letters inside (some letters cut their way into a word).
'heel' becomes 'list' (both can mean to tilt).
'nine' reversed gives 'enin'.
'enin' going into 'list' is 'LENINIST'.
'which' acts as a link.
(Other definitions for leninist that I've seen before include "Type of Marxist" , "left-wing, in a way" , "Red" , "Bolshevik" , "Revolutionary" .)