Inaugurate by oath (5,2)
I believe the answer is:
swear in
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">inaugurate by oath</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 swear in that I've seen before include "Administer official oath" , "Admit to office" , "Get into office" , "Inaugurate by oath" , "bring candidate to office" .)