Red nose turning back (7)
I believe the answer is:
endorse
'back' is the definition.
(back can mean to support or endorse)
'red nose turning' is the wordplay.
'turning' indicates anagramming the letters.
'red'+'nose'='rednose'
'rednose' anagrammed gives 'ENDORSE'.
(Other definitions for endorse that I've seen before include "Give backing to" , "Support; sanction" , "Give public approval of (something)" , "Approve officially" , "Back, sanction" .)