The most common and most likely answer to this crossword clue is the 9 letter word OPEN-EYED
I've seen this crossword clue in The Guardian
O
P
E
N
-
E
Y
E
D
More clues leading to the result OPEN-EYED
- Astonished old writer spotted
- Old writer — look down and be amazed
- Watchful old marshal’s into weed
- Aware of Cockney’s ambition, yen to stop inadequacy
- Public looked attentive
- Astonished by work in French? I’d say
- Blindfolded? On the contrary, quite watchful!
- Peon was confused and looked alert
- Alert public getting opening to needle Democrat
- Astonished to be awake?
Buddy explains!

The straight part
We know that "Watchful" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case watchful = open-eyed.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does OPEN-EYED mean?
OPEN-EYED adjective- Alert and vigilant