The entire north-eastern quadrant, a section measuring roughly 17 metres by 21.5 metres, has been quarried out to a depth of about three metres, leaving an abrupt void where the enclosing bank once curved around. It is that absence, as much as what remains, that defines the site today.

Ringforts, known in Irish as raths when constructed from earth rather than stone, were the most common form of enclosed farmstead in early medieval Ireland, typically housing a single family and their livestock within a circular bank and ditch. The Cloonbrone example sits on a gentle rise in pasture land, with the ground falling away gradually to the south and east, the kind of elevated position that would have given its original occupants clear sightlines over the surrounding grassland. The earthen bank survives across the arc from south-east to north, though in a reduced state, reaching an external height of around 1.45 metres on the western side and about 1.1 metres to the south-east. Internally, the bank registers as little more than a low lip, between 0.2 and 0.4 metres high, with the structure presenting more convincingly as a scarp when viewed from outside. The overall diameter of the enclosure is approximately 38 metres. A later field bank running on a north-south axis butts up against the south-western section of the rath, and its line continues northward through the western half of the interior, now marked by a post and wire fence, a reminder that the land has been folded into ordinary agricultural use for a long time since the rath's original purpose was forgotten.