Don't know about hiving out but to hive off means to remove from a larger unit or group; form into or assign (work) to a subsidiary department or company; denationalize or privatize (an industry, etc.) (OED)
A quote from James Howard Kunstler's book, "The Geography of Nowhere":
Typically, an early Massachusetts town was organized with individually owned home lots around a fenced common used to pen livestock. Townships were granted whole congregations who crossed the ocean as a group, bringing with them highly localized customs and farming practices. There if a minority couldn't abide the way a town was run, they could resolve their problem by "hiving out" to some unsettled area, always in a group, and creating a way of life with which they were at ease.
Kunstler, The Geography of Nowhere, page 20
Cited to Kostof, America by Design, page 297