Figure out exactly where you are having challenges. It might even only be a note or two.
Figure out what is causing the problem. Is it an awkward fingering? A difficult interval? If playing an instrument with a pick or bow, do you you need to change the movement as you play that difficult section? If singing, is it your breathing?
Come up with more than 1 solution to the problem. This might be in your breathing, fingering, pick or bow movement, being relaxed, changing the notes to a different location on the fretboard, etc.
Once you’ve found a solution, use a metronome to play it slowly and then build up speed.