Английский словарь американских идиом - clean slate

{n. phr.} A record of nothing but good conduct, without any errors or bad deeds; past acts that are all good without any bad ones. * /Johnny was sent to the principal for whispering. He had a clean slate so the principal did not punish him./ * /Mary stayed after school for a week, and after that the teacher let her off with a clean slate./ Compare: TURN OVER A NEW LEAF.