Group using a bottle opener at church (5)
I believe the answer is:
batch
'group' is the definition.
(a batch is a group or set)
'a bottle opener at church' is the wordplay.
'opener' suggests taking the first letters.
'church' becomes 'ch' (common abbreviation).
The initial letter of 'bottle' is 'b'.
'b'+'at'+'ch'='BATCH'
'using' is the link.
(Other definitions for batch that I've seen before include "Group of objects prepared or sent together" , "Production run" , "All the bread baked at the same time" , "Production quantity" , "Group of items (as handled)" .)