Loud, a church clock (4)
I believe the answer is:
face
'clock' is the definition.
(thesaurus)
'loud a church' is the wordplay.
'loud' becomes 'f' (short for forte - 'loud' in music).
'church' becomes 'ce' (Church of England).
'f'+'a'+'ce'='FACE'
(Other definitions for face that I've seen before include "Watch's dial" , "Cope with" , "celebrity" , "'Cheeks, mouth, eyes etc (4)'" , "Confront - mug (slang)" .)