The headword is the present imperative of the verb dusxerai/nw, evidently quoted from somewhere (perhaps Marcus Aurelius, Meditations 10.3, where it occurs twice, though there are other possibilities).
This injunction is usually employed in the negative: mh\ dusxe/raine.
[1] cf. a scholion on Gregory of Nazianzus, PG 36.1241a (and see generally LSJ s.v. for other, commoner usages).
[2] For this gloss cf. alpha 822.