Young kangaroo (4)
I believe the answer is:
joey
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">young kangaroo</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for joey that I've seen before include "Young kangaroo" , "Sydney's youngster" , "jumper, in a pocket?" , "Baby boomer's" , "Threepenny bit" .)