Retribution! Gene bashed in van at church (9)
I believe the answer is:
vengeance
'retribution' is the definition.
(synonyms)
'gene bashed in van at church' is the wordplay.
'bashed' indicates an anagram.
'in' is an insertion indicator.
'at' is a charade indicator (letters next to each other).
'church' becomes 'CE' (abbreviation for Church of England).
'gene' is an anagram of 'enge'.
'enge' placed within 'van' is 'vengean'.
'vengean'+'ce'='VENGEANCE'
(Other definitions for vengeance that I've seen before include "Retribution" , "Retributory punishment" .)