The Book of Irish Names, First Family & Place Names has Clare listed as a honorary name for St. Clare of Assisi (1193-1253). The Irish county of Clare in Munster derives from either clar , "plain", or from the Anglo-Norman name of de Clare .

According to the History of Family Names --the names CLEAR, CLEARE, CLEERE, (and I suspect CLERE --NCR), are variations of CLARE.  Clare is French-Latin; Fr. Clair , Lat. Clar-us .  But the English and Anglo-Saxon Clares get their name from the Norman family of St. Clair or de Clare.  St. Clair is a common French place-name. Clare in Suffolk came from the castle of Gilbert de Clare. His sister married the Earl of Ulster bringing the Lordship of Clare into the family.

Several sources mention Richard de Clare (1130-1176), the second Earl of Pembroke who was the leader of the Anglo-Norman invasion of Ireland under William the Conqueror.  De Clare who was nicknamed "Strongbow", led the invasion in 1171.

Clear and Clare were sometimes used in place of the Irish O'Cleary during the time of the Gaelic suppression when many Irish families changed their surname to a more English sounding one.  Rev. Fr. Wallace Clare (1895-1963) was the founder of the Irish Genealogical Society.