Lead-in to zone (4)
I believe the answer is:
euro
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">lead-in to zone</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 euro that I've seen before include "Ready, in many places" , "Common currency unit" , "Major currency" , "Currency of Austria" , "Currency of Finland" .)