Ahuyenta means "drives away" or "scares away." It's a vivid verb that implies actively chasing something away, rather than just making it disappear.
In "Enamorada," the singer uses ahuyenta to describe how a loving gaze can "drive away" or "scare away" sadness and pain. It paints a picture of love as a powerful force that actively combats sorrow, making it a memorable and emotionally resonant word in the context of the song.