What does the cryptic crossword clue "Alter original opinion amending chosen reforms (6,4,4)" mean?

The wordplay uses an anagram. anagram of AMENDING + CHOSEN = CHANGEONESMIND The answer is CHANGEONESMIND.

Alter original opinion amending chosen reforms (6,4,4)

Daily Mail Cryptic #17058 | 6 Across | 2023-03-21 flower