River swallowed up woven fabric (7)
I believe the answer is:
taffeta
'woven fabric' is the definition.
'taffeta' can be an answer for 'fabric' (taffeta is a kind of fabric). I am not sure about the 'woven' bit.
'river swallowed up' is the wordplay.
'river' becomes 'taff' (river in Wales).
'swallowed' becomes 'ate' (swallow can mean to eat).
'up' says the letters should be written backwards (in down clue: letters go upwards).
'ate' back-to-front is 'eta'.
'taff'+'eta'='TAFFETA'
Can you help me to learn more?
(Other definitions for taffeta that I've seen before include "cloth" , "Fabric - fat fate (anag)" , "silky stuff" , "Shiny fabric for fat fate" , "Crisp, smooth, lustrous fabric" .)