The most common and most likely answer to this crossword clue is the 9 letter word HEXAGONAL
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The straight part
We know that "with several sides" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case with several sides = hexagonal.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 HEXAGONAL mean?
HEXAGONAL adjective- Having six edges, or having a cross-section in the form of a hexagon.
- Having three equal axes which cross at 60° angles, and an unequal axis which crosses the others at 90° angle.