Share a side (4)
I believe the answer is:
abut
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">share a side</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for abut that I've seen before include "Lie adjacent to" , "Adjoin -- 19 (rev)" , "Neighbour" , "Be next to -- share a boundary" , "Touch upon" .)