make a clean breast of something, to

make a clean breast of something

If you make a clean breast of something, you tell the whole truth about it. `But what shall I tell my parents?' — `You'll have to make a clean breast of it, dear.' If you make a clean breast of your problems, creditors are much more likely to deal fairly with you.
See also: breast, clean, make, of, something
Collins COBUILD Idioms Dictionary, 3rd ed.

make a clean breast of something (or of it)

confess your mistakes or wrongdoings.
In former times, many people believed that the breast or chest was where a person's conscience was located. The breast is still used metaphorically to represent the seat of the emotions.
See also: breast, clean, make, of, something
Farlex Partner Idioms Dictionary

make a clean ˈbreast of something

admit fully something that you have done wrong: He decided to make a clean breast of it and tell the police.
See also: breast, clean, make, of, something
Farlex Partner Idioms Dictionary

make a clean breast of something, to

To make a full confession. The word breast here is a synonym for “heart,” long considered the seat of private emotion and, by extension, secrets. Shakespeare referred to cleansing one’s bosom in Macbeth (5.3). The current cliché dates from the early eighteenth century.
See also: breast, clean, make, of
The Dictionary of Clichés by Christine Ammer
See also:
  • clean (someone or something) out of (something)
  • clean out of
  • you could eat off the floor(s)
  • swab out
  • clean-up operation
  • operation
  • clean someone out
  • clean out
  • clean up
  • (as) clean as a hound's tooth