Be amazed (at) (6)
I believe the answer is:
marvel
'be amazed at' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for marvel that I've seen before include "Cause of wonder" , "Wonderful person or thing" , "Wonderful thing/person" , "Be filled with wonder - something wondrous" , "Wonderful or astonishing person" .)