Hallucinatory experience produced by drug? Nonsense (5)
I believe the answer is:
tripe
'nonsense' is the definition.
(informal term for nonsense or false information)
'hallucinatory experience produced by drug?' is the wordplay.
'hallucinatory experience' becomes 'trip' (as in tripping on drugs).
'produced by' says to put letters next to each other.
'drug?' becomes 'e' (E is another name for ecstasy).
'trip'+'e'='TRIPE'
(Other definitions for tripe that I've seen before include "Bunk" , "Rhubarb" , "Junk; food" , "Rubbish; offal" , "Garbage" .)