turban, conical cap
幘 centers on a specific type of headwear: a turban or conical cap. Both meanings describe a wrapped or shaped cloth covering for the head.
幘 combines 巾 (cloth) with 責, which likely contributes the sound. The character refers to a cloth head covering, consistent with the 巾 component.
The left side 巾 is a cloth, and the right side 責 looks like a person wearing a tall, wrapped headpiece. Picture wrapping a long cloth around the head to form a turban or conical cap.
For サク, imagine tying a turban so tightly it makes a 'sack' shape on the head: sack -> サク, and the cloth wraps into a conical cap.