vb. (context idiomatic English) To engage in self-improvement; to begin a good habit or shed a bad habit.
Usage examples of "turn over a new leaf".
A good day to turn over a new leaf, for the day after to-morrow is New Year’.
He didn't have much to say about his wife, however, except that he was going to turn over a new leaf.
What Champollion will decipher this hieroglyphic for us, that we may turn over a new leaf at last?
What's more, if you turn over a new leaf, and keep it turned, I'll cook you some taters one of these days.
I got him punished-just at n time when he began to try and turn over a new leaf too!