Post Excerpt as SEO Description

You can use the %%excerpt%% template variable. You can configure your template settings for pages/posts by going to SEO>Search Appearance>Content Types and then inputting the template variable for the ‘Meta Description’. We also have additional information on using the title template variables as well as a full list of which variables are available for use at the following link: https://kb.yoast.com/kb/yoast-wordpress-seo-titles-metas-template-variables/

Thank you very much for the quick reply @devnihil, that’s awesome!