The headword (presumably extracted from the quotation given) is aorist indicative active, third person singular, of e)ggua/w; cf. epsilon 165, epsilon 168, epsilon 169, epsilon 170.
[1] Theophylact Simocatta, Histories 8.3.2, on Roman general Priscus's strategy during the second of a series of battles against the Avars (see generally alpha 18 note) in 599; cf. de Boor (287) and Whitby (212). The precise locations of these engagements remain unknown, but they took place along the banks of the Danube opposite the city of Viminacium (near modern-day Kostolac, eastern Serbia; cf. Barrington Atlas map 21 grid D5); cf. Whitby (211-212 note). On Priscus, see PLRE IIIb s.v. Priscus(6).