Pay Rip erroneously for writing materials (6)
I believe the answer is:
papyri
'writing materials' is the definition.
'papyri' can be an answer for 'materials' (papyrus is a kind of material). I am not certain of the 'writing' bit.
'pay rip erroneously' is the wordplay.
'erroneously' indicates an anagram.
'pay'+'rip'='payrip'
'payrip' with letters rearranged gives 'PAPYRI'.
'for' is the link.
Can you help me to learn more?
(Other definitions for papyri that I've seen before include "writing stuff" , "writer's out-of-date material" , "Documents of old" , "Old manuscripts" .)