1
general::
Phrase(s): make a clean breast of something (to someone)
Fig. to admit something to someone. • You should make a clean breast of the matter to someone. • You’ll feel better if you make a clean breast of the incident.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Confess fully, as in Caught shoplifting, the girls decided to make a clean breast of it to their parents. This expression, first recorded in 1752, uses clean breast in the sense of baring of one's heart, the breast long considered the seat of private or secret feelings.
American Heritage Idioms