The most common and most likely answer to this crossword clue is the 8 letter word SHREWDER
I've seen this crossword clue in The Daily Telegraph
S
H
R
E
W
D
E
R
More clues leading to the result SHREWDER
Buddy explains!

The straight part
We know that "more crafty" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case more crafty = shrewder.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 SHREWDER mean?
SHREWDER adjective- Showing clever resourcefulness in practical matters.
- Artful, tricky or cunning.
- Streetwise.
- Knowledgeable, intelligent, keen.
- Nigh accurate.
- Severe, intense, hard.
- Sharp, snithy, piercing.
- Bad, evil, threatening.
- Portending, boding.
- Noxious, scatheful, mischievous.
- Abusive, shrewish.
- Scolding, satirical, sharp.