Drug, uplifting white powder's striking effect (5)
I believe the answer is:
eclat
'striking effect' is the definition.
(I've seen this before)
'drug uplifting white powder's' is the wordplay.
'drug' becomes 'e' (E is another name for ecstasy).
'uplifting' is a reversal indicator.
'white powder' becomes 'talc' (I've seen this before).
'talc' reversed gives 'clat'.
'e'+'clat'='ECLAT'
(Other definitions for eclat that I've seen before include "Social distinction in France" , "Universal approval" , "Ostentation" , "brilliant effort" , "Splash" .)