How to use Display Suite to trim whitespace from a field
Sorry for the digression — but semantic markup does matter. This articles speaks well to what it is: https://boagworld.com/dev/semantic-code-what-why-how/ 

Your input filter (or, less possibly, your rich text editor) is adding the paragraph tag. Check out the input filter you're using for this field. If this filter has "Convert line breaks into HTML (i.e. &lt;br&gt; and &lt;p&gt;)" enabled, found here: admin/config/content/formats/&lt;inputfiltername&gt; — this could be adding paragraph tags. Keep in mind changing this will impact how all your fields that use this input filter are rendered. You can always create an additional input filter to suite your needs.