The most common and most likely answer to this crossword clue is the 6 letter word MEMOIR
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More clues leading to the result MEMOIR
Buddy explains!

The straight part
We know that "Biography" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case biography = memoir.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 MEMOIR mean?
MEMOIR noun- An autobiography; a book describing the personal experiences of an author.
- A biography; a book describing the experiences of a subject from personal knowledge of the subject or from sources with personal knowledge of the subject.
- Any form of narrative describing the personal experiences of a writer.