Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.
CLANCY
As described in historical dictionaries
Patronymica Britannica (1860)
CLANCY. An Irish clan tributary to the O'Brian. D'Alton.
Origin: Celtic
Region of origin: British Isles
Country of origin: Ireland
Religion of origin: Christian
Language of origin: Gaelic