Startled description of one who's wide-awake (4-4)
I believe the answer is:
open-eyed
This could be a double definition.
'startled description of one' is the first definition.
The answer and definition are not the same part of speech. However, past participle verbs and adjectives occasionally mean the same thing.
'wide-awake' is the second definition.
(thesaurus)
'who's' acts as a link.
Can you help me to learn more?
(Other definitions for open-eyed that I've seen before include "Astonished - watchful" , "Forming an encrusted mass" , "Surprised - aware" , "Astonished; fully aware" .)