Stare dumbfoundedly (4)
I believe the answer is:
gape
'stare dumbfoundedly' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for gape that I've seen before include "Gawp" , "Stare stupidly" , "Yawn" , "wide opening" , "Look at with wide-open mouth" .)