Flimsy stuff made from purest sepia fragments (6,5)
I believe the answer is:
tissue paper
'flimsy stuff' is the definition.
(flimsy material)
'purest sepia fragments' is the wordplay.
'fragments' is an anagram indicator (the fragments are put back together differently).
'purest'+'sepia'='purestsepia'
'purestsepia' with letters rearranged gives 'TISSUE-PAPER'.
'made from' acts as a link.
(Other definitions for tissue paper that I've seen before include "Wrapping for delicate objects" , "There may be a valuable article in it!" , "Kleenex" , "delicate sheets" .)