You once flipped, getting into cannabis, ecstasy and mescal (6)
I believe the answer is:
peyote
'mescal' is the definition.
('peyote' can be a synonym of 'mescal')
'you once flipped getting into cannabis ecstasy' is the wordplay.
'you once' becomes 'ye' (I've seen this in other clues).
'flipped' says the letters should be written in reverse.
'getting into' is an insertion indicator.
'cannabis' becomes 'pot' ('pot' can be a synonym of 'cannabis').
'ecstasy' becomes 'e' (informal term for the drug).
'ye' written backwards gives 'ey'.
'ey' placed within 'pot' is 'peyot'.
'peyot'+'e'='PEYOTE'
'and' acts as a link.
(Other definitions for peyote that I've seen before include "Cactus hallucinogen" , "Hallucinogenic drug from Mexican cactus" , "Mescal, a cactus" , "Hallucinogenic cactus; eye pot (anag.)" .)