Resounding effect bible classes have, perhaps (6)
I believe the answer is:
reverb
'resounding effect' is the definition.
'reverb' can be an answer for 'effect' (I have seen 'Musical effect' mean 'reverb' so perhaps 'effect' could also mean 'reverb'). I am not certain of the 'resounding' bit.
'bible classes have perhaps' is the wordplay.
I cannot really understand how this works, but
'bible' could be 'ev' (abbreviation for English Version of the Bible) and 'ev' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for reverb that I've seen before include "Musical device producing echoes" , "Musical effect produced via an amplifier" , "Sound prolongation" , "Electronic device" , "Echoing device" .)