Party: go to one to consume drugs (6)
I believe the answer is:
fiesta
'party' is the definition.
(I know that fiesta is a type of party)
'go to one to consume drugs' is the wordplay.
'go' becomes 'fit' (synonyms).
'to one' becomes 'a' (a thing is one thing).
'to consume' indicates putting letters inside.
'drugs' becomes 'es' (ecstasy tablets).
'fit'+'a'='fita'
'fita' enclosing 'es' is 'FIESTA'.
(Other definitions for fiesta that I've seen before include "(Iberian) religious holiday" , "Saint's day; carnival" , "Latin American celebration" , "A Spanish public celebration" , "Festival, fete" .)