A good hour sat around, horrified (6)
I believe the answer is:
aghast
'horrified' is the definition.
(I know that horrified can be written as aghast)
'a good hour sat around' is the wordplay.
'good' becomes 'g' (abbreviation).
'hour' becomes 'h' (abbreviation).
'around' is an anagram indicator.
'sat' anagrammed gives 'ast'.
'a'+'g'+'h'+'ast'='AGHAST'
(Other definitions for aghast that I've seen before include "Confounded" , "Deeply dismayed" , "Taken aback with horror" , "Very unhappy" , "Filled with consternation or horror" .)