One acted to change account (8)
I believe the answer is:
anecdote
'account' is the definition.
(anecdote is a kind of account)
'one acted to change' is the wordplay.
'to change' is an anagram indicator.
'one'+'acted'='oneacted'
'oneacted' is an anagram of 'ANECDOTE'.
(Other definitions for anecdote that I've seen before include "A short tale, usually true" , "A short amusing story, probably true" , "Brief story" , "Short narration" , "One acted over interesting story" .)