Nuclease required for the repair of DNA interstrand cross-links (ICL) (PubMed:24192486, PubMed:25319828). Acts as a 5'-3' exonuclease that anchors at a cut end of DNA and cleaves DNA successively at every third nucleotide, allowing to excise an ICL from one strand through flanking incisions (By similarity). Hydrolytically removes 5'-nucleotides successively from the 3'-hydroxy termini of 3'-hydroxy-terminated oligonucleotides. Binds 2 magnesium or manganese ions per subunit. Hypersensitivity to a cross-linking agent. Belongs to the FAN1 family.