The headword phrase (likewise unglossed in other lexica: references at Photius omicron418 Theodoridis) is evidently extracted from somewhere, perhaps Plutarch, Moralia 392E (On the 'E' at Delphi) 392E: "Time: Indeed, wherever 'latter', 'former', 'it shall be', or 'it has become' is being said, there is an immediate admission of non-being."
On the combined emphatic force of the particles ge and dh/, see Denniston pp. 244-6.