Nobody taking drug after midday (2-3)
I believe the answer is:
no-one
'nobody' is the definition.
(not a single person)
'drug after midday' is the wordplay.
'drug' becomes 'e' (E is another name for ecstasy).
'after' says to put letters next to each other.
'midday' becomes 'noon' (synonyms).
'e' put after 'noon' is 'NO-ONE'.
'taking' is the link.
(Other definitions for no-one that I've seen before include "Not a soul" , "Nobody" , "Not a single person" , "Not one person" .)