This rectangular hall-keep, measuring roughly 13 metres north to south and 18.5 metres east to west, was built from locally quarried limestone rubble with walls reaching an impressive 2.5 metres thick. Though only the northern, southern and eastern walls survive today, standing two storeys high, the structure once featured a northeast corner tower and sophisticated defensive elements including a prominent base-batter and chamfered quoinstones, particularly visible at the southeast corner.

The castle's original design reveals the careful planning typical of medieval strongholds. The main entrance, positioned at the eastern end of the south wall, was accessed at first-floor level, likely via a wooden staircase from a small fore-building whose foundations can still be traced against the southeast corner. Once inside, visitors would have found themselves in a first-floor chamber lit by windows set deep within segmental-arched embrasures. A doorway in the southeast angle led to a mural staircase ascending to either a second floor or wall-walk, whilst another opening in the northeast corner provided access to the now-destroyed tower. The ground floor, reached by an internal wooden stair, was illuminated only by narrow slit openings and later modified with a large doorway inserted through the north wall.

Beyond the main structure, remnants of the castle's wider defensive complex can still be discerned. To the west, an earthen bank reduced in places to a two-metre-high scarp shows traces of drystone wall facing on its external surface, marking what was likely the boundary of the original bailey or enclosure area associated with the hall-keep. These fragmentary remains, though poorly preserved, help paint a picture of Clohaskin as more than just an isolated tower; it was once the centrepiece of a larger fortified settlement that commanded this corner of medieval Tipperary.