The most common and most likely answer to this crossword clue is the 8 letter word TRIALLED
I've seen this crossword clue in The Daily Telegraph
T
R
I
A
L
L
E
D
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.
What does TRIALLED mean?
TRIALLED verb- To carry out a series of tests on (a new product, procedure etc.) before marketing or implementing it.
- To try out (a new player) in a sports team.