Brief month on ecstasy with soft, sweet drink (5)
I believe the answer is:
julep
'sweet drink' is the definition.
(I've seen this in another clue)
'brief month on ecstasy with soft' is the wordplay.
'brief month' becomes 'jul' (abbreviation for July; 'brief' asks for an abbreviation).
'on' is a charade indicator (letters next to each other).
'ecstasy' becomes 'E' (informal term for the drug).
'with' means one lot of letters go next to another.
'soft' becomes 'p' (musical abbreviation for 'piano').
'jul'+'e'+'p'='JULEP'
(Other definitions for julep that I've seen before include "Mint drink in America" , "Sweet drink, often medicated" , "See 21 Down" , "Cocktail of bourbon, sugar and mint over crushed ice" , "(Minted) drink made with bourbon, sugar and crushed ice" .)