Same or similar entry in other lexica; see the references at Photius kappa813 Theodoridis. The headword is present middle/passive participle, masculine accusative singular or neuter nominative/accusative singular, of knai/w, a variant of kna/w.
The sense of this verb is inferred by lexicographers from compound verbs, as the verb is not well-attested on its own in classical Greek. (It is used in Plutarch, On Superstition 170B, citing an ancient verse referring to the pains of childbirth, and LSJ suggests it as an emendation to kainiei= in Ecclesiasticus 38:28 LXX -- Rahlfs instead uses klinei=. Otherwise the verb on its own is used only by grammarians.)
To this instance we can add kappa 1857 (q.v.); ps.-Zonaras s.v. knai/w "grieve", and Philoxenus fr. 120 "ruin" (cited in Etymologicum Gudianum s.v. kluzw=sai).
The participle here and its gloss might be extrapolated from (?)Aeschylus, Prometheus Bound 541 muri/ois mo/xqois diaknaio/menon "worn away by a myriad cares". The sense "cut" can be inferred from the literal sense of diaknai/w "scrape away", as in Euripides, Cyclops 486 lampra\n o)/yin diakna/sei "gouge out his bright sight".
For the glossing verb cf. under tau 1116.