Red nose treated in second (7)
I believe the answer is:
endorse
'second' is the definition.
(I know that second can be written as endorse)
'red nose treated' is the wordplay.
'treated' indicates an anagram.
'red'+'nose'='rednose'
'rednose' with letters rearranged gives 'ENDORSE'.
'in' is the link.
(Other definitions for endorse that I've seen before include "Give one's sanction to" , "Approve or underwrite" , "'Approve of, back (7)'" , "Say you approve" , "Give support or approval to" .)