The most common and most likely answer to this crossword clue is the 2 plus 9 letter word EN SPECTACLE
E
N
S
P
E
C
T
A
C
L
E
Buddy explains!
The straight part
We know that "As a sight to see in Paris" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case as a sight to see in paris = en spectacle.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.