Sauce only served in pub by church (9)
I believe the answer is:
insolence
'sauce' is the definition.
(thesaurus)
'only served in pub by church' is the wordplay.
'only' becomes 'sole' ('sole' can be a synonym of 'only').
'served in' is an insertion indicator.
'pub' becomes 'inn' (I've seen this before).
'by' is a charade indicator (letters next to each other).
'church' becomes 'ce' (abbreviation for Church of England).
'sole' placed into 'inn' is 'insolen'.
'insolen'+'ce'='INSOLENCE'
(Other definitions for insolence that I've seen before include "Lip; cheek" , "Rudeness, impudence" , "freshness" , "Front" , "Rudeness, disrespect" .)