lay down, put down
擱 centers on placing something down deliberately: laying an object down or putting it aside.
擱 combines 扌 (hand) with 閣, which likely contributes the sound カク. The hand radical suggests the action of placing or setting something down.
The hand radical 扌 beside 閣 (a tall building or shelf) suggests a hand placing something onto a shelf or laying it down carefully.
For カク, imagine putting down a heavy cask: cask -> カク, and your hand lowers it onto the shelf.