Material used when writing intro Yeats devised (10)
I believe the answer is:
stationery
'material' is the definition.
(stationery is a kind of material)
'intro yeats devised' is the wordplay.
'devised' indicates an anagram.
'intro'+'yeats'='introyeats'
'introyeats' is an anagram of 'STATIONERY'.
'used when writing' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for stationery that I've seen before include "The papers, etc" , "Pens, pencils, paper etc" , "Writer's needs" , "Treasury tags, for instance" , "Writing material" .)