Young people take drugs into strange building (9)
I believe the answer is:
teenagers
'young people' is the definition.
(people aged between twelve and twenty)
'drugs into strange building' is the wordplay.
'drugs' becomes 'ee' (an abbreviation for ecstasy written twice).
'into' means one lot of letters goes inside another.
'building' indicates anagramming the letters.
'strange' with letters rearranged gives 'tnagers'.
'ee' going within 'tnagers' is 'TEENAGERS'.
'take' acts as a link.
(Other definitions for teenagers that I've seen before include "Adolescents" , "They're between the onset of puberty and maturity, generally" , "They're aged between 13 and 19" , "Youngsters" , "Young people" .)