Words one put down in worn-out blotter (8)
I believe the answer is:
libretto
'words' is the definition.
(I've seen this before)
'one put down in worn-out blotter' is the wordplay.
I cannot really see how this works, but
'one' could be 'i' (Roman numeral) and 'i' is located in the answer.
an anagram of 'blotter' is 'lbretto' which is present in the remaining letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for libretto that I've seen before include "The words of an opera or musical play" , "Operatic book" , "Text written for an opera" , "Opera's words" , "Book of words of an opera" .)