John Gill Commentary Judges 17:7

"And there was a young man out of Beth-lehem-judah, of the family of Judah, who was a Levite; and he sojourned there." — Judges 17:7 (ASV)

And there was a young man out of Bethlehemjudah
As there were two Bethlehems, one in the tribe of Zebulun, (Joshua 19:15) and another in the tribe of Judah, the place here designed, Judah is added to it, to distinguish it from the other:

of the family of Judah :
This refers either to the young man, who was by his father's side a Levite, and by his mother's side, as Jarchi thinks, of the tribe of Judah, which seems very probable, though the genealogies of families were not reckoned from the mother. So he might be so called because he had lived chiefly in the tribe of Judah, and particularly at Bethlehem. But Kimchi, and several other Jewish commentators, refer this to the city of Bethlehem, that was of the tribe of Judah, family being put for the tribe, or belonged to the children of Judah, though one would think there was no need to have added this, since it was fully expressed before by calling it Bethlehemjudah; the former sense therefore seems best.

who was a Levite ;
his father being, as before observed, of that tribe, though his mother might be of the tribe of Judah: and he sojourned there; that is, at Bethlehem; he was not a native, nor an inhabitant there, but a sojourner, it not being a Levitical city.