Intoxicated by pupils who are superior (4-5)
I believe the answer is:
high-class
'are superior' is the definition.
(I've seen this before)
'intoxicated by pupils' is the wordplay.
'intoxicated' becomes 'high' (similar in meaning).
'by' says to put letters next to each other.
'pupils' becomes 'class' (I've seen this before).
'high'+'class'='HIGH-CLASS'
'who' acts as a link.
(Other definitions for high-class that I've seen before include "Posh" , "Superior" .)