The most common and most likely answer to this crossword clue is the 8 letter word BLOTTING
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Buddy explains!

The straight part
We know that "sort of paper" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sort of paper = blotting.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 BLOTTING mean?
BLOTTING verb- To cause a blot (on something) by spilling a coloured substance.
- To soak up or absorb liquid.
- To dry (writing, etc.) with blotting paper.
- To spot, stain, or bespatter, as with ink.
- To impair; to damage; to mar; to soil.
- To stain with infamy; to disgrace.
- To obliterate, as writing with ink; to cancel; to efface; generally with out.
- To obscure; to eclipse; to shadow.
- A blot; a stain.
- The process by which something is blotted.