Come or go in (5)
I believe the answer is:
enter
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">come</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ >'<span class="explanation-format__original">go in</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(as in entering a building)</span><br/ ><br/ ></span>
(Other definitions for enter that I've seen before include "Fruit drink" , "Enlist, join up" , "cross the threshold" , "Pierce" , "Come or go in" .)