The most common and most likely answer to this crossword clue is the 7 letter word FUSTIAN
F
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S
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I
A
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The straight part
We know that "material" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case material = fustian.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 FUSTIAN mean?
FUSTIAN noun- A kind of coarse twilled cotton or cotton and linen stuff.
- A class of cloth including corduroy and velveteen.
- Pompous, inflated or pretentious writing or speech.
- A drink made of white wine with egg yolk, lemon and spices.