The most common and most likely answer to this crossword clue is the 5 plus 2 plus 3 plus 4 letter word QUICK ON THE DRAW
I've seen this crossword clue in The Daily Telegraph
Q
U
I
C
K
O
N
T
H
E
D
R
A
W
More clues leading to the result QUICK ON THE DRAW
Buddy explains!
The straight part
We know that "Sharp/as a sketch artist" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sharp/as a sketch artist = quick on the draw.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.