It sprinkles holy water in breathing apparatus, according to initiates (9)
I believe the answer is:
aspergill
'it sprinkles holy water in breathing apparatus' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.
'according to initiates' is the wordplay.
'according to' becomes 'asper' (I've seen this before).
'initiates' becomes 'gill' (I can't explain this - if you can you should give a lot more credence to this answer).
'asper'+'gill'='ASPERGILL'
Can you help me to learn more?
(Another definition for aspergill that I've seen is " sprinkler".)