How do I loop a clip in Ableton Session view?
Playing the clip and then clicking the Set Loop Position button moves the beginning of loop to the current playback position (rounded to the global quantization setting) and engages the loop. Then, clicking the Set Loop Length button moves the end of the loop to the current playback position.
How do I enable loops in Ableton?
For Live to repeatedly play a section of the Arrangement, activate the Arrangement loop by clicking on the Control Bar's Loop switch. The Loop Start Fields (Left) and the Loop Length Fields (Right).