Go in (5)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">go in</span>' is the definition.<br/ ><span class="explanation-format__explanation">(as in entering a building)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for enter that I've seen before include "A key on the right" , "Treen (anag.)" , "Go/come in" , "cross the threshold" , "submit?" .)
(Other definitions for offer that I've seen before include "Chance to buy at reduced price?" , "Submit" , "killer?" , "Tender for acceptance" , "Propose; make available" .)