Child's word for sleep (3-4)
I believe the answer is:
bye-byes
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">child's word for sleep</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for bye-byes that I've seen before include "(Child's word for) sleep" , "Informal repetitive farewells" , "Sleep for little children" .)