The most common and most likely answer to this crossword clue is the 15 letter word CHICKEN-AND-EGG
I've seen this crossword clue in Independent
C
H
I
C
K
E
N
-
A
N
D
-
E
G
G
Buddy explains!
The straight part
We know that "Puzzling situation" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case puzzling situation = chicken-and-egg.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.