Make A Clean Breast Meaning
(intransitive, idiomatic) to be honest about something; to confess
Example: 1886, Robert Louis Stevenson, Strange Case Of Dr Jekyll And Mr Hyde
"It is well, then that we should be frank," said the other. "We both think more than we have said; let us make a clean breast. This masked figure that you saw, did you recognise it?"
1915, John Buchan, The Thirty-Nine Steps
Then suddenly I thought of another probability. Supposing I went out now and called in the police, or went to bed and let Paddock find the body and call them in the morning. What kind of a story was I to tell about Scudder? I had lied to Paddock about him, and the whole thing looked desperately fishy. If I made a clean breast of it and told the police everything he had told me, they would simply laugh at me.
(Can we date this quote?) 20,000 Leagues Under the Seas Chapter 43
"Master," he said that day to me, "this must come to an end. I must make a clean breast of it. This Nemo is leaving land and going up to the north. But I declare to you that I have had enough of the South Pole, and I will not follow him to the North."