"of upright character and healthful habits, mentally and morally healthy," 1874, from the noun phrase; see clean (adj.) + living (n.).
Clean Living is opposed to anything and everything which speaks for physical and mental disorder, dirt, disease, distress and discontent. Clean Living stands for babies, better born and better bred, better clothed and better fed; happier, healthier babies with normal play, normal environment and a normal chance to live and develop. Clean Living stands for youth, the critical time, the unfolding time, the time when muscle, mind, morals and manners of the boy and girl shall start right or wrong, for health and success or disease and failure. ["Clean Living," vol. I, no. 1, April 1916, Chicago]