Archaic greeting (3,4)
I believe the answer is:
all hail
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">archaic greeting</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 all hail that I've seen before include "dire weather forecast" , "that may greet one" , "Appalling weather" , "Archaic greeting" , "that greeted Macbeth" .)