Separator "-" issue

Hi !

I need to change this: ABBA-Mamma Mia to this: ABBA - Mamma Mia

Many of my mp3 files have no space between artist and tittle and others have one space. I want all of them with a single space.

How do I can fix it ?

Action type: Replace with regular expressions
Regular expression: \s*-\s*
Replace matches with: " - " (without quotes)