Thread quietly lost in morphia's delirium (6)
I believe the answer is:
mohair
'thread' is the definition.
(thesaurus)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for mohair that I've seen before include "Angora goat yarn" , "Fabric from coating of angora goat" , "Fabric made from silky hair of angora goat" , "Cloth made from wool of angora goat" , "Fabric made from fine silky wool of goat" .)