Aristocratic senior pupils, perhaps (5,5)
I believe the answer is:
upper class
'aristocratic' is the definition.
(I've seen this before)
'senior pupils perhaps' is the wordplay.
I cannot really understand how this works, but
'pupils' could be 'class' (I've seen this before) and 'class' is found in the answer.
The remaining letters 'upper' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for upper class that I've seen before include "Aristocratic" , "Posh" , "Top social echelon" .)