Have great confidence in (5,2)
I believe the answer is:
swear by
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">have great confidence in</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 swear by that I've seen before include "Express great confidence in" , "Rely on" , "Have utter faith in" , "Have total faith in" .)