recording a mono track while playing imported music

Mac Catalina and Audacity 2.4.2

I am trying to record a bass clarinet part onto a mono track while playing the piece on a stereo track that I imported. My mono track is recording but I cant hear the imported piece of music. How do I set Audacity to allow me to hear the imported song while recording my part? Thanks

Tick “play other tracks while recording (overdub)” …

Also available in “Transport menu > Transport options > Overdub (on/off)”.