The most common and most likely answer to this crossword clue is the 11 letter word STARRY-EYED
S
T
A
R
R
Y
-
E
Y
E
D
Buddy explains!
The straight part
We know that "Naively optimistic" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case naively optimistic = starry-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 STARRY-EYED mean?
STARRY-EYED adjective- Having naively optimistic hopes or outlooks.