Eccentric group concealing drug in Arthur's place (7)
I believe the answer is:
camelot
'arthur's place' is the definition.
(court of King Arthur)
'eccentric group concealing drug' is the wordplay.
'eccentric' becomes 'cam' (eccentric cam is a type of mechanical part).
'group' becomes 'lot'.
'concealing' is an insertion indicator.
'drug' becomes 'e' (E is another name for ecstasy).
'cam'+'lot'='camlot'
'camlot' going around 'e' is 'CAMELOT'.
'in' is the link.
(Other definitions for camelot that I've seen before include "King Arthur court - or JFK's" , "King Arthur's court - or JFK's" , "Fabulous city" , "Arthur's or Kennedy's court?" , "King Arthur's town" .)