Bring down the prescribed amount - about the final low volume (6)
I believe the answer is:
depose
'bring down' is the definition.
'depose' can be an answer for 'bring' (thesaurus). I am unsure of the 'down' bit.
'the prescribed amount about the final low volume' is the wordplay.
'the prescribed amount' becomes 'dose' (I've seen this before).
'about' means one lot of letters goes inside another.
'the final low volume' becomes 'ep' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'dose' enclosing 'ep' is 'DEPOSE'.
Can you help me to learn more?
(Other definitions for depose that I've seen before include "Force out of office" , "Oust from throne" , "Remove from office or position" , "Set down" , "Attest and force off a throne" .)