Officially inform (6)
I believe the answer is:
notify
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">officially inform</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for notify that I've seen before include "alert" , "Officially inform" , "Formally tell" , "No one" , "Declare" .)