Wrong tense instructed orally (4)
I believe the answer is:
tort
'wrong' is the definition.
(legal term)
'tense instructed orally' is the wordplay.
'tense' becomes 't' (grammatical abbreviation).
'instructed orally' becomes 'ort' (I can't explain this - if you can you should give a lot more credence to this answer).
't'+'ort'='TORT'
Can you help me to learn more?
(Other definitions for tort that I've seen before include "Small tropical fish" , "Trot to get legal wrong" , "Legal wrong for which damages may be sought" , "Trot after legal offence" , "Trot after legal wrong liable to damages" .)