Stand up for notes' conclusion (6)
I believe the answer is:
defend
'stand up for' is the definition.
(I've seen this in another clue)
'notes' conclusion' is the wordplay.
'notes'' becomes 'de' (two musical notes).
'conclusion' becomes 'fend' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'de'+'fend'='DEFEND'
Can you help me to learn more?
(Other definitions for defend that I've seen before include "Block, as in cricket" , "Justify" , "Maintain against attack" , "Protect or assist against attack" , "Safeguard" .)