Hallucinogen obtained from fermented stale dung (5,4)
I believe the answer is:
angel dust
'hallucinogen' is the definition.
(angel dust is a kind of hallucinogen)
'fermented stale dung' is the wordplay.
'fermented' indicates anagramming the letters.
'stale'+'dung'='staledung'
'staledung' with letters rearranged gives 'ANGEL DUST'.
'obtained from' acts as a link.
(Other definitions for angel dust that I've seen before include "Drug" , "Hallucinogen - stale dung (anag)" .)