The most common and most likely answer to this crossword clue is the 4 plus 9 letter word RUDE AWAKENING
I've seen this crossword clue in The Daily Telegraph
R
U
D
E
A
W
A
K
E
N
I
N
G
Buddy explains!
The straight part
We know that "The reality" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case the reality = rude awakening.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.