Set to be in church (5)
I believe the answer is:
batch
'set to' is the definition.
(I've seen this before)
'be in church' is the wordplay.
'be in' becomes 'bat' (the person batting is 'in' in cricket).
'church' becomes 'ch' (common abbreviation).
'bat'+'ch'='BATCH'
(Other definitions for batch that I've seen before include "Arrange things in groups" , "Items produced together" , "All the bread baked at the same time" , "Production quantity" , "Production run" .)