Refrain from turning sour after church (6)
I believe the answer is:
chorus
'refrain' is the definition.
(I know that refrain can be written as chorus)
'turning sour after church' is the wordplay.
'turning' indicates anagramming the letters.
'after' is a charade indicator (letters next to each other).
'church' becomes 'ch' (common abbreviation).
'sour' anagrammed gives 'orus'.
'orus' put after 'ch' is 'CHORUS'.
'from' acts as a link.
(Other definitions for chorus that I've seen before include "Speak in unison" , "Singing group - refrain" , "Dramatic team" , "Group singing together" , "Sing together" .)