This is a reformulation of Orion's etymology διὰ τὸ τὰ νάματα ἀφελεῖν ἐκ τῆς θαλάσσης (see νεφέλη / νᾶμα + ἀφαιρέω), which may be considered an improvement since it avoids the manipulation in the first member of the compound: the segmentation is ν-εφέλη, and ἑφέλκω accounts for the [e] in the first syllable. The etymology implies dropping the [k], which is not commented upon. From the semantic point of view, the etymology is similar to Orion's: the cloud takes water out of the sea to bring it to the land.