Artificial fibre that's not long-lasting (5)
I believe the answer is:
brief
'long-lasting' is the definition.
Both the answer and definition are adjectives. Perhaps you can see a link between them that I can't see?
'artificial fibre that's not' is the wordplay.
'fibre' can be anagrammed to 'BRIEF'.
However, I'm unsure how the anagram is indicated.
Can you help me to learn more?
(Other definitions for brief that I've seen before include "Case given to a barrister" , "Summary of facts for barrister to consider" , "Concise; short-lived" , "not lasting long" , "Using few words" .)