The most common and most likely answer to this crossword clue is the 5 letter word NOILS
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Buddy explains!
The straight part
We know that "Bits of fibre" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case bits of fibre = noils.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 NOILS mean?
NOILS noun- A short fibre left over from combing wool or spinning silk during the preparation of textile yarns. Sometimes it is referred to as 'Raw Silk', although this is somewhat of a misnomer.