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

The straight part
We know that "Knowingly" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case knowingly = shrewdly.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 SHREWDLY mean?
SHREWDLY adverb- In a shrewd manner.