The most common and most likely answer to this crossword clue is the 8 letter word TWIDDLES
I've seen this crossword clue in The Guardian
T
W
I
D
D
L
E
S
More clues leading to the result TWIDDLES
Buddy explains!

The straight part
We know that "fiddles" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case fiddles = twiddles.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 TWIDDLES mean?
TWIDDLES verb- To wiggle, fidget or play with; to move around.
- To flip or switch two adjacent bits (binary digits).
- To be in an equivalence relation with.
- To play with anything; hence, to be busy about trifles.