Your biggest bet here is going to depend on your ability / access to APIs for said calendar.
If you have an "HTML Snippet" of drop-in code, you can drop it into an HTML Tile.
If you only have API access, then you'll need to recreate the experience and populate a Custom View Tile with Sharepoint code.
See: Creating Custom View Tiles to get started there.
If you wanted to the calendar to appear in a more contextually relevant location, you may also consider looking at the following:
which shows where all an App can manifest inside Jive. Albeit, this may be overkill ... but if you wanted to pursue this option...you'd simply need to start with Getting Started > Creating an App with the Jive Node SDK
Hope that helps.