When you import an audio clip with consistent timing and don't know the exact tempo or length in bars and beats, it's easy to get it synced to your project. Start by double clicking on the event so that it opens in the sample editor and choosing the Audio Tempo Definition Tool. If necessary click at the beginning of the event with the tool or grab the left locator to position the beginning of the first bar just before the transient of the first downbeat in the audio clip.

Now click and grab the vertical line at the start of the second bar in the timeline and line it up with the downbeat at the beginning of the second bar in the audio file. This will warp the rest of the editor's timeline to this tempo. It can also be a good idea to check a few bars later and if necessary adjust the timing in a similar way there and at a few more points toward the end of the clip to make sure the timing is actually on. The actual original tempo of the audio file will now be indicated in the "audio tempo" box within the sample editor.

Now click the "Musical Mode" icon to allow the audio to warp to project tempo (take note of the "warp setting" dropdown menu where you can choose timestretch quality) and close the sample editor. The audio will now snap and adapt to your project tempo.