An anchored entity is a brand-new entity that is linked to another referent which is not brand new by means of the inclusion of a referring expression in the noun phrase.
In the following expression, guy (brand new) is anchored to the speaker (not brand new) by the phrase I work with:
Prince, Ellen F. 1981. "Toward a taxonomy of given-new information." In Cole, P. 1981 223–255.