For the entry cf. the scholia to Homer, Iliad 9.173 and Odyssey 18.422, where the headword participle occurs; also (e.g.) Herodian, Schematismi Homerici 108. Again at epsiloniota 7.
The form is an Aeolic dialect form of the perfect participle active of a(nda/nw 'please, give pleasure to', used in the masculine accusative singular as an adjective to mu/qon in the Homeric phrase "he had told them a tale that had pleased them."
On one point the entry is in error, for the form does not contain a dissolution but reflects the loss in Greek of the initial cluster sw-, present in this root's derivatives in English (sweet) and Latin (suavis). This initial is reduplicated in the perfect, and then lost. See Lexikon des frühgriechischen Epos 2.799.26-31 for the phonological history of the word and 2.892.7-9, 51-54 for cognates. The long alpha and loss of the rough breathing in Homer is to be explained as an Aeolic dialect form (Chantraine, Grammaire homérique 20).
[1] This paradigm is of the present stem of an active verb 'give pleasure', a secondary formation from the familiar verb h(/domai 'take pleasure', a verb with a different history but from the same root as the previous, cf. Chantraine, Dictionnaire étymologique 406.
[2] The perfect participle active of a(nda/nw is here given in three singular cases, nominative, genitive and the accusative of the headword.