The most common and most likely answer to this crossword clue is the 8 letter word NANOTUBE
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More clues leading to the result NANOTUBE
Buddy explains!

The straight part
We know that "its cylindrical form" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case its cylindrical form = nanotube.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 NANOTUBE mean?
NANOTUBE noun- Shortening of carbon nanotube; A carbon molecule, in the shape of a tube, having a fullerene structure and a diameter of about 1 or 2 nanometers.
- Any nanotech tubular structure with a characteristic diameter measured in a few nanometres, such as titanium nanotubes