You could potentially change the clip to start at an later part of the clip, like go to the source editor and choose where it starts. You can do that by clicking the wave symbol next to the sound in the contents editor. Or you can do it, like I do, and test the sound prior to even putting it into Wwise. For example using audacity or audition to make sure the audio is good on looping. The later I find much more useful because, if there is a hick up you can easily find a way to fix it, instead of re-importing to Wwise.