make one's bones

make one's bones (third-person singular simple present makes one's bones, present participle making one's bones, simple past and past participle made one's bones)

1. (idiomatic) To commit a murder in order to be respected in a criminal gang.
   • 1976, Gloria Vitanza Basile, The Godson, page 232:

     Mario Cacciatore was fourteen when he made his bones.

2. (idiomatic, by extension) To establish one's bona fides; to establish status and respect.
   • 2018 January 18, Eric Bradner and Chris Cillizza, "Republicans are running in 2018. Running from Trump", CNN.com (retrieved 4 September 2018):

     Politicians—good ones, at least—make their bones by knowing which way the wind is blowing.