Astounded (6)
There are a few possibilities for this:
gobsmacked
'astounded' is the definition.
('amaze' can be a synonym of 'astound')
This is all the clue.
(Other definitions for amazed that I've seen before include "Overwhelmed with wonder" , "Staggered" , "Flabbergasted" , "Awe-struck" , "Greatly surprised, astounded" .)
'astounded' is the definition.
(thesaurus)
This is all the clue.
(Other definitions for aghast that I've seen before include "Horror-stricken, filled with consternation" , "Thunderstruck" , "Amazed" , "Stupefied with horrer" , "What's carried in bag has teacher" .)
'astounded' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for gobsmacked that I've seen before include "Amazed" , "shocked" , "bowled over" , "Flabbergasted" , "Stunned" .)