The most common and most likely answer to this crossword clue is the 11 letter word CALCULATING
I've seen this crossword clue in The Daily Telegraph
C
A
L
C
U
L
A
T
I
N
G
Buddy explains!

The straight part
We know that "Devious/computing" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case devious/computing = calculating.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 CALCULATING mean?
CALCULATING verb- To determine the value of something or the solution to something by a mathematical process.
- To determine values or solutions by a mathematical process; reckon.
- To plan; to expect; to think.
- To ascertain or predict by mathematical or astrological computations the time, circumstances, or other conditions of; to forecast or compute the character or consequences of.
- To adjust for purpose; to adapt by forethought or calculation; to fit or prepare by the adaptation of means to an end.
- Having the ability to calculate.
- (especially of a person) Serving one's own interests in an unemotional, analytical manner.