Exhausted by the more advanced classes? (5)
I believe the answer is:
upper
'advanced classes?' is the definition.
The answer and definition are different parts of speech. However, past participle verbs and adjectives can sometimes define each other.
'exhausted by the more' is the wordplay.
'exhausted' becomes 'up' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'by' becomes 'per'.
'the more' is a charade indicator (letters next to each other) (some letters added to the previous ones).
'up'+'per'='UPPER'
Can you help me to learn more?
(Other definitions for upper that I've seen before include "catcher of swans?" , "The higher of two, berths perhaps" , "Higher in position; drug" , "Part of a shoe; drug" , "Higher in status" .)