Line on fabric (5)
I believe the answer is:
rayon
'fabric' is the definition.
(rayon is a kind of fabric)
'line on' is the wordplay.
'line' becomes 'ray' (ray is a kind of line**).
'ray'+'on'='RAYON'
(Other definitions for rayon that I've seen before include "Man-made fibre" , "Viscose fabric" , "Synthetic material" , "Artificial fibre" , "Silklike material" .)