Lifted plump cheese to find crisp material (7)
I believe the answer is:
Here is my best explanation:
'crisp material' is the definition.
(type of crisp silk)
'lifted plump cheese' is the wordplay.
'lifted' shows that the letters should be reversed in order (going up in down clue).
'plump' becomes 'fat' ('fat' can be a synonym of 'plump').
'cheese' becomes 'feta' (I've seen this before).
'fat' back-to-front is 'taf'.
'to find' acts as a link.
(Other definitions for taffeta that I've seen before include "fine material for dressing", "Stiff shiny material", "cloth", "Shiny fabric for fat fate", "Fine crisp lustrous fabric", "fine stuff indeed!", "The shiny silklike fabric", "silky stuff", "Smooth, stiff fabric" and "Fabric -- a fat eft (anag)".)