Bullet for a Star by Stuart M. Kaminsky (Mysterious Press 1977)

My face was in my favor. I badly needed a haircut, but sometimes the slightly wild look was just what a client wanted in a bodyguard. My nose had been broken at least three times, once by a baseball thrown by my brother, once by a wind-shield and once by a fist thrown by my brother, in that order. But at five foot nine, the nose was a valuable asset. It announced that I had known violence.