Found drug in packing case (6)
I believe the answer is:
create
'found' is the definition.
(thesaurus)
'drug in packing case' is the wordplay.
'drug' becomes 'e' (e is another name for ecstasy).
'in' means one lot of letters goes inside another.
'packing case' becomes 'crate' (I've seen this before).
'e' inserted inside 'crate' is 'CREATE'.
(Other definitions for create that I've seen before include "Build" , "Concoct" , "Produce from nothing" , "found" , "Compose" .)