What is Clerical Error?

Legal Definition
A clerical error is an error on the part of an office worker, often a secretary or personal assistant. It is a phrase which can also be used as an excuse to deflect blame away from specific individuals, such as high-powered executives, and instead redirect it to the more anonymous clerical staff.

A clerical error in a legal document is called a scrivener's error.
-- Wikipedia
Legal Definition
An error made by a clerk in transcribing or otherwise. This is always readily corrected by the court. 2. An error, for example, in the teste of a fi. fa.; 4 Yeates, 185, 205; or in the teste and return of a vend. exp.; 1 Dall. 197 or in writing Dowell forMcDowell. 1 Serg. & R. 120; 8 Rep. 162 a; 9 Serg. & R. 284, 5. An error is amendable where there is something to amend by, and this even in a criminal case. 2 Bin. 5-16; 5 Burr. 2667; 1 Bin. 367-9; Dougl. 377; Cowp. 408. For the party ought not to be harmed by the omission of the clerk; 3 Bin. 102; even of his signature, if he affixes the seal. 1 Serg. & R. 97.
-- Bouviers Law Dictionary
Legal Definition
A mistake in writing or copying; the mistake of a clerk or writer. 1 Ld. Raym. 183,
-- Black's Law Dictionary
Legal Definition
A copyist’s error; a slip of the pen.
-- Ballentine's Law Dictionary