Church with a role to play in disease (7)
I believe the answer is:
cholera
'disease' is the definition.
(cholera is a kind of disease)
'church with a role to play' is the wordplay.
'church' becomes 'ch' (common abbreviation).
'with' is a charade indicator (letters next to each other).
'to play' indicates anagramming the letters.
'a'+'role'='arole'
'arole' is an anagram of 'olera'.
'ch'+'olera'='CHOLERA'
'in' acts as a link.
(Other definitions for cholera that I've seen before include "Oh, Clare has highly infectious disease" , "A severe intestinal disease, severe Asiatic kind" , "Disease contracted from infected water" , "Deadly, infectious disease" , "could kill you" .)