Provides material to refute (8)
I believe the answer is:
disprove
'refute' is the definition.
(synonyms)
'provides material' is the wordplay.
'material' indicates an anagram (the letters provide the material for a new word).
'provides' anagrammed gives 'DISPROVE'.
'to' acts as a link.
(Other definitions for disprove that I've seen before include "Refute, rebut" , "challenge successfully?" , "Negate" , "Demonstrate to be false" , "Show to be false - so provide" .)