Display Screen or Portion Thereof with an Animated Icon

FIG. 1 is a front view of a display screen or portion thereof with an animated icon; and, FIG. 2 is a front view of second image thereof. The outermost broken lines shown in the FIGURES illustrate portions of the display screen or a portion thereof with an animated icon that form no part of the claimed design. The appearance of the display screen or portion thereof with with an animated icon transitions sequentially between the views shown in FIGS. 1 and 2 respectively. The process or period in which one FIGURE transitions to another forms no part of the claimed design.