Original sentence: The head of the powerful, but exiled, Alcmaeonid family, Cleisthenes, began to scheme to overthrow Hippias and return to Athens
Edited sentence: The head of the powerful, but exiled (according to Herodotus only - the fragmentary Archon List for 525/4 shows a Cleisthenes, an Alcmaeonid, holding office in Athens during this period), Alcmaeonid family, Cleisthenes, began to scheme to overthrow Hippias and return to Athens