The most common and most likely answer to this crossword clue is the 5 letter word RAMIE
I've seen this crossword clue in Independent
R
A
M
I
E
More clues leading to the result RAMIE
- Grass that is given to sheep
- Herb that is submerged under butter
- I brought in ream, after pulping source of paper
- Plant that is trodden on by sheep
- China grass – with butter, that is
- Herb that is buried under stuff
- Marie tailored cloth
- Royal French beloved's fabric
- Butter with rice, every other herb
- Marie replaced plant
Buddy explains!

The straight part
We know that "source of paper" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case source of paper = ramie.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 RAMIE mean?
RAMIE noun- (usually countable) A tall, tropical Asian perennial herb, Boehmeria nivea, cultivated for its fibrous stems.
- (usually uncountable) fibre extracted from this plant, resembling flax.