Have doubts about teacher tied up in hearing (8)
I believe the answer is:
mistrust
'have doubts about' is the definition.
(I've seen this before)
'teacher tied up in hearing' is the wordplay.
'teacher' becomes 'mis' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'tied up' becomes 'trussed' ('truss' can be a synonym of 'tie up').
'in hearing' shows a homophone (sound like).
'trussed' is a homophone of 'trust'.
'mis'+'trust'='MISTRUST'
Can you help me to learn more?
(Other definitions for mistrust that I've seen before include "Have doubts about" , "Have no confidence in (someone)" , "Lack of belief (in someone)" , "Regard with suspicion" , "reservations" .)