Roofing slab (4)
I believe the answer is:
tile
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">roofing slab</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for tile that I've seen before include "Flat piece of ceramic" , "Roofing or flooring item" , "Hat" , "Mah-jong piece" , "Ceramic slab for roofs, walls, floors etc" .)