Sponsored Topics. Clancy is a census-designated place (CDP) in Jefferson County, Montana, United States. The population was 1,406 at the 2000 census. It is part of the Helena Micropolitan Statistical Area. Clancy is located at 46°28′29″N 111°59′1″W / 46.47472°N 111.98361°W / 46.47472; -111.98361 (46.474638, -111.983497).