Enables 5'-3' exonuclease activity. Involved in protection from non-homologous end joining at telomere; telomeric 3' overhang formation; and telomeric loop formation. Located in chromosome, telomeric region. Is expressed in brain. Orthologous to human DCLRE1B (DNA cross-link repair 1B). [provided by Alliance of Genome Resources, Apr 2022]