"Variant of McLean"
The name Mcclain is commonly a unisex name.
Mcclain is an anglicized Scottish and Irish surname, one of several spellings of Gaelic Mac Gille Eathain, glossed as "son of the servant of John." The same element underlies the surnames McLean and MacLean, and the Mc- spelling points to an Irish or Galloway transmission. It is recorded in United States birth records as a given name from 1918.
McLean means "Traditional name".
The pronunciation of Mcclain is muh-KLANE.