The most common and most likely answer to this crossword clue is the 2 plus 1 plus 4 plus 3 plus 7 letter word AS I LIVE AND BREATHE
A
S
I
L
I
V
E
A
N
D
B
R
E
A
T
H
E
Buddy explains!
The straight part
We know that "Wow!" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case wow! = as i live and breathe.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.