Working man reacts to ceremony (9)
I believe the answer is:
sacrament
'to ceremony' is the definition.
(sacrament is a kind of ceremony)
'working man reacts' is the wordplay.
'working' indicates an anagram.
'man'+'reacts'='manreacts'
'manreacts' with letters rearranged gives 'SACRAMENT'.
(Other definitions for sacrament that I've seen before include "Religious rite" , "Religious ceremony" , "Symbol of something spiritual" , "baptism, say" , "Church ritual imparting divine grace" .)