Crossword Genius

In prison cubicle at Seoul, lost some rayon base (9)

Ross

I believe the answer is:

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(Other definitions for cellulose that I've seen before include "O cull eels for what causes the pitted look", "Polysaccharide", "dietary fibre", "film-makers use it", "Substance in plants -- so cull eel (anag)".)

I've seen this clue in Sydney Morning Herald.