Can I use the music from Clips in iMovie?
The only way I see possible is the following:


Choose the music you want in Clips.
Record a clip that’s at least as long as the music you want (you could always hold then swipe up on the record button and come back 5 minutes later if you’re not sure how long the music clip is).
Select the clip you just recorded and tap “Mute.”
Tap the Share button and tap “Copy to iMovie.” (Yes, we’ll eventually get it to iMovie on macOS).
In iMovie for iOS, trim the clip to the desired length.
Tap “Done” then tap the share button, then tap “Save Video.”
Once the video has exported, go to Photos on your iOS device and select the clip you just exported. Tap the share button, then air drop it to your Mac. You could also use the photos app on your Mac to import the clip if you wish.
On your Mac, open iMovie and drag in the clip.
Click, then Two-finger-click the clip, then click, “Detach Audio.”
Drag the audio to be attached to a different clip.
Click, then Two-finger-click the video clip, then hit “delete” on your keyboard. Now you can drag the audio wherever you want to use it in your Project.


Let me know if any of that doesn’t make sense. I tested it using iPad mini 4 on iOS 11 and MacBook Pro with high sierra before posting so I know it works.