Share a border with, be next to (4)
I believe the answer is:
abut
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">share a border with</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >'<span class="explanation-format__original">be next to</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ ></span>
(Other definitions for abut that I've seen before include "Meet" , "Lean against the odd tuba" , "Adjoin, press up against" , "Touch, lean on" , "Touch upon" .)