Bow in a church (3)
I believe the answer is:
arc
'bow' is the definition.
(both can mean a curve)
'a church' is the wordplay.
'church' becomes 'RC' (abbreviation for Roman Catholic).
'a'+'rc'='ARC'
'in' is the link.
(Other definitions for arc that I've seen before include "Segment of circle" , "Section of circumference" , "Electric discharge" , "Electrical spark" , "development of plot" .)