The most common and most likely answer to this crossword clue is the 11 letter word CONSEQUENCE
I've seen this crossword clue in The Guardian
C
O
N
S
E
Q
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C
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More clues leading to the result CONSEQUENCE
Buddy explains!

The straight part
We know that "Note" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case note = consequence.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does CONSEQUENCE mean?
CONSEQUENCE noun- That which follows something on which it depends; that which is produced by a cause.
- A result of actions, especially if such a result is unwanted or unpleasant.
- A proposition collected from the agreement of other previous propositions; any conclusion which results from reason or argument; inference.
- Chain of causes and effects; consecution.
- Importance with respect to what comes after.
- The power to influence or produce an effect.
- (especially when preceded by "of") Importance, value, or influence.
- To threaten or punish (a child, etc.) with specific consequences for misbehaviour.