Composer's church work, popular (6)
I believe the answer is:
chopin
'composer's' is the definition.
(Chopin is an example)
'church work popular' is the wordplay.
'church' becomes 'ch' (common abbreviation).
'work' becomes 'op' (abbreviation for opus).
'popular' becomes 'in'.
'ch'+'op'+'in'='CHOPIN'
(Other definitions for chopin that I've seen before include "Polish pianist-composer" , "Double centenarian" , "See 10" , "Writer of music" , "No chip on this composer's shoulder" .)