Mostly annoy university representative, hard to disapprove (8)
I believe the answer is:
harrumph
'hard to disapprove' is the definition.
I can't judge whether this defines the answer.
'mostly annoy university representative' is the wordplay.
'mostly' means to remove the last letter.
'annoy' becomes 'harry' (harrying is a kind of annoying).
'university representative' becomes 'umph' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'harry' with its last letter removed is 'harr'.
'harr'+'umph'='HARRUMPH'
Can you help me to learn more?
(Other definitions for harrumph that I've seen before include "Express grumpy opposition" , "Clearing of the throat - expression of dissatisfaction" , "Make disapproving sound" , "Clear one's throat noisily" , "Sound of someone clearing throat" .)