Forty lies ruined autobiography (4,5)

I believe the answer is:

life story

'autobiography' is the definition.
(thesaurus)

'forty lies ruined' is the wordplay.
'ruined' indicates an anagram.
'forty'+'lies'='fortylies'
'fortylies' with letters rearranged gives 'LIFE STORY'.

(Other definitions for life story that I've seen before include "Autobiography" , "Biography" .)

I've seen this clue in The Times.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.