Tavern by church introduces fish sauce (9)
I believe the answer is:
insolence
'sauce' is the definition.
(thesaurus)
'tavern by church introduces fish' is the wordplay.
'tavern' becomes 'inn' (I've seen this before).
'by' says to put letters next to each other.
'church' becomes 'ce' (abbreviation for Church of England).
'introduces' is an insertion indicator.
'fish' becomes 'sole' (sole is a kind of fish**).
'inn'+'ce'='innce'
'innce' enclosing 'sole' is 'INSOLENCE'.
(Other definitions for insolence that I've seen before include "Lip; cheek" , "freshness" , "Rude disrespect" , "Disrespectful behaviour" , "Front" .)