This is a Buffering icon. We've made it in iOS style, first introduced in iOS version 7 and supported in all later releases up until now (at least iOS 11). This style is based on thin two-pixel lines and is optimized for 50x50 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 12,600 icons, all in the same style and quality.
This icon for "spinner frame 6" is a group of eight circles. These circles are arranged to form a single large circle. The eight smaller circles are different in shape, with the smallest one being on the left, and each circle getting progressively larger in a clockwise manner.