There doesn't seem to be a way to clear an entire queue on the Spotify app on either device without just removing each individual app. I've seen that a clear button has been added in the past (sometime in 2017) but it isn't there anymore. I just updated my Spotify app on my mac today, and there definitely isn't an option to clear the whole queue. I can click a song by another artist to play, and then it goes back to the queue, which is usually fine, but then if I don't want to listen to Sara Bareilles anymore, I have to clear each song one by one. Any ideas about a work around?
There is a live idea similar to yours here. You can vote for it and add your thoughts in the comments. At the moment the status of the idea is "Good idea", meaning that internal teams are checking the votes and comments.
In the meantime, you can find some possible workaround in this thread.