The most common and most likely answer to this crossword clue is the 10 letter word EMENDATION
I've seen this crossword clue in The Guardian
E
M
E
N
D
A
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Buddy explains!
The straight part
We know that "change for the better" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case change for the better = emendation.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 EMENDATION mean?
EMENDATION noun- The act of altering for the better, or correcting what is erroneous or faulty; correction; improvement.
- Alteration by editorial criticism, as of a text so as to give a better reading; removal of errors or corruptions from a document.
- An intentional change in the spelling of a scientific name, which is usually not allowed.