The most common and most likely answer to this crossword clue is the 8 plus 5 letter word SPENDING SPREE
I've seen this crossword clue in The Times
S
P
E
N
D
I
N
G
S
P
R
E
E
More clues leading to the result SPENDING SPREE
Buddy explains!
The straight part
We know that "retail therapy?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case retail therapy? = spending spree.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.