On An Island In The Sun

I am new to Affinity Designer and have a question about something I am trying to achieve in the program. I am uploading a screenshot of what I'm trying to do and have a question about - which is trim the uneven edges of an object or outlined font glyph using another shape - a circle - so that the glyphs perimeter will be refined and no longer imperfect. Please view the screenshot for more detailed information. Thank You.