One cad upset churchman (6)
I believe the answer is:
deacon
'churchman' is the definition.
(I've seen this before)
'one cad upset' is the wordplay.
'upset' indicates anagramming the letters.
'one'+'cad'='onecad'
'onecad' with letters rearranged gives 'DEACON'.
(Other definitions for deacon that I've seen before include "Church officer" , "An ordained minister" , "Churchman" , "Church minister" , "Layman attending to church duties" .)