Note article cannot be reduced (6)
I believe the answer is:
minima
'cannot be reduced' is the definition.
I can't judge whether this defines the answer.
'note article' is the wordplay.
'note' becomes 'minim' (type of musical note).
'article' becomes 'a' (the indefinite article in English).
'minim'+'a'='MINIMA'
Can you help me to learn more?
(Other definitions for minima that I've seen before include "Lowest quantity or amount" , "Lowest possible amounts" , "bottoms" , "Smallest possible amounts" , "unbeatable prices?" .)