Little map on a big map (5)
I believe the answer is:
inset
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">little map on a big map</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 inset that I've seen before include "Stein (anag)" , "subsidiary diagram" , "Small map within larger; teacher training day" , "Gore" , "Small picture placed within a larger one" .)