Crossword Genius

Material from river reportedly turning up negative (5)

Ross

I believe the answer is:

nylon

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'material' is the definition.
(nylon is a kind of material)

'river reportedly turning up negative' is the wordplay.
'river reportedly' becomes 'lyn' (I am not sure about this - if you are sure you should believe this answer much more).
'turning' is a reversal indicator.
'up' is a reversal indicator (in down clue: letters go upwards).
'negative' becomes 'no' (no is a kind of negative).
'lyn' reversed gives 'nyl'.
'no' in reverse letter order is 'on'.
'nyl'+'on'='NYLON'

'from' is the link.

Can you help me to learn more?

(Other definitions for nylon that I've seen before include "Hosiery material" , "Man-made fibre" , "A thermoplastic" , "may be damaged by running" , "where ladder can appear?" .)

I've seen this clue in The Telegraph.
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