I suggest playing it through the Alexa app until Alexa learns that is the podcast that you want. In the Alexa app, tap the Play icon, tap Browse Music, choose TuneIn, then type in the name of the podcast in the search box.
You may have to do this a few dozen times until Alexa learns about your tastes in music or podcasts. There are times when Alexa will never learn it. Nothing you can do about it.
By the way, why did you neglect to post the name of the podcast? Wouldn't you think it could make it a lot easier for the folks on here to help you when they know what you are looking for. Unless the podcast is something perverted or embarrassing...