an axe to grind
Axe to Grind. To have a grievance with someone, especially where one feels the need to seek damaging retribution. The phrase probably originates from the act of sharpening an axe with a grinding wheel, with the intent (in this definition) to get revenge on someone by maiming or killing them. ;) Five years ago that guy stole my idea for an invention and made tons of money off it! I've had an axe to grind with him ever since.