[2] Her paternal grandfather, Amos Hargrett (1833-1905), was born into slavery but went on to hold a number of political offices and was one of the few African-American delegates to the Florida Constitutional Convention of 1885.

Andrew Hargrett, whose son dubbed him a "Frontier Professor", became an itinerant teacher and later school principal who supplemented his income through farming, fishing, and carpentry.

[5] Clack taught for seven years in public high schools in Gadsden, Leon, and Wakulla counties in the Florida Panhandle.

After earning her master's degree, she started working for the Florida A&M University library, eventually heading the cataloging and technical services divisions.

One of her students wrote of Clack: She had always been so elegant, tall and fashionably dressed, with a milk chocolate complexion, a beautiful smile, and regal posture [...] she was serious about cataloging and firm, even strict, in teaching us the discipline.

In what was described as "perhaps the height of her career", she organized the International Conference on AACR2 in March 1979, which featured Seymour Lubetzky, Michael Gorman, and numerous other figures pivotal in the development of AACR2.