Wonderful thing (6)
I believe the answer is:
marvel
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">wonderful thing</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 marvel that I've seen before include "Gaze, wonder" , "Wonder, be astonished" , "Wondrous thing" , "Wonderful thing/person" , "Feel sense of wonder and awe" .)