bone to pick, have a
An unpleasant issue or grievance that needs discussion. For example, Concerning the room assignments, I have a bone to pick with you. This metaphoric term alludes to a dog worrying a bone. [Early 1500s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.