Likewise or similarly in other lexica (but sometimes with textual corruption: see Photius, Lexicon pi2108 Theodoridis). The correct headword, as here, is aorist imperative of e)ne/pw, used in the epic formula e)/spete nu=n moi, *Mou=sai ... "tell me, Muses ..." (four times in the Iliad, e.g. 2.284; also in the Homeric Hymns and Hesiod).
Probably from *e)/n-spete with zero-grade of the root *sekw-; cf. epsilon 1351.