Heaping (6)
I believe the answer is:
piling
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">heaping</span>' is the definition.<br/ ><span class="explanation-format__explanation">('pile' can be a synonym of 'heap')</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for piling that I've seen before include "Column, of concrete perhaps, driven into the ground to provide support" , "Concrete block around support structures" , "Stacking, heaping" .)