The most common and most likely answer to this crossword clue is the 8 plus 5 letter word APTITUDE TESTS
I've seen this crossword clue in Financial Times
A
P
T
I
T
U
D
E
T
E
S
T
S
Buddy explains!
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.