Quietly affect water-bearer (4)
I believe the answer is:
pail
'water-bearer' is the definition.
I can't tell whether this defines the answer.
'quietly affect' is the wordplay.
'quietly' becomes 'p' (musical symbol).
'affect' becomes 'ail' (I can't explain this - if you can you should give a lot more credence to this answer).
'p'+'ail'='PAIL'
Can you help me to learn more?
(Other definitions for pail that I've seen before include "water-carrier" , "Milkmaid's bucket?" , "Vessel for carrying liquids" , "A bucket - the kind Jack and Jill used" , "it may go down well" .)