オク, や, た
roof, house, shop, dealer, seller
JLPT4 G3 S9 F616
至 here a variant of 侯# (lumpy object) + 尸 shape indicator (→ cover) → lumpy covering object, such as the *roof* of a *house* or *shop* → *cover*; *business*. Also, *dealer* and *seller* (← the same semantic progression from "house/place of business" to "tradesman" as found in 家).
[Full Kanji Etymology List]