The headword is perfect middle passive participle, masculine nominative singular, of the verb e)calei/fw. Usually this verb has the sense of 'wipe out, obliterate'; the present entry, however, perhaps derives from ancient comment on Thucydides 3.20.3 (web address 1), where the equivalent neuter participle is used in a sense appropriate to the gloss given here (of the "unplastered" city wall at Plataiai).
cf. Hesychius epsilon3535.