The most common and most likely answer to this crossword clue is the 5 plus 8 letter word SHARP PRACTICE
I've seen this crossword clue in The Daily Telegraph
S
H
A
R
P
P
R
A
C
T
I
C
E
More clues leading to the result SHARP PRACTICE
- Dishonest dealings rare in talented singers?
- Dodgy dealings exposed by astute medical centre
- Sneaky behaviour from clever jerk engaged in dodgy caper
- Do angels have to do it after start of show? It’s a bit naughty
- Distinct cost about pretence and chicanery
- Slow to drop unscrupulous regular string pulling and chicanery
- Pointed performance included in cost is cheating
- Unscrupulous behaviour in music rehearsal?
- Keen — before rehearsal shows cheating
- What pianist needs to get to manage black notes? Sly execution
Buddy explains!
The straight part
We know that "Sly execution" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sly execution = sharp practice.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.