Thanks, Brian Dornbusch, for asking your question. And Mehtaz Afsana Borsha for providing an answer which gave me pointers to creating a workaround for my problem of wanting to include a podcast link with social icons on my website based on the Helix Ultimate template.
But first, I already use the Social Icons Custom field for displaying a seach icon (fa-search /search). It annoyed me that the icon opened a new tab. However, Mehtaz, your agethemes linked article showed me where to go to remove the target="blank", in Templates -> (Shaper_helixultimate) -> features -> social.php -> function renderFeature().
Then I realised rather thank define $vk (which already exists), I could "tweak" it by adding my podcast's URL to in the Social Icons VK Username field and replacing the span class="fa fa-vk" with "fa fa-microphone".
Perfect! Just need to remember to make the custom changes whenever I update the Helix Ultimate template.
Here is a like to my website if you're interested, TallAndTrue.com.au. (I've made the changes and tested them on a staging version - it'll take me an hour to populate them on the live website.)
Regards, and thanks again,
Robertf