Look amazed (4)
I believe the answer is:
gape
'look amazed' is the definition.
(to gape is to stare open-mouthed in amazement)
This is all the clue.
(Other definitions for gape that I've seen before include "Look at with wide-open mouth" , "Failure to meet" , "Look open-mouthed" , "Gawp" , "Look in amazement or stupidity" .)