Expansive, immense (4)
I believe the answer is:
vast
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">expansive</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">immense</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I know that immense can be written as vast)</span><br/ ><br/ ></span>
(Other definitions for vast that I've seen before include "Extremely large or extensive" , "Of very great extent" , "Colossal" , "Huge, enormous" , "'Huge, immense (4)'" .)