Assuming high opinion of own self, exerted leverage in speech (5)
I believe the answer is:
pride
'assuming high opinion of own self exerted leverage in speech' is the definition.
I can't judge whether this defines the answer.
'assuming high opinion of own self' is the wordplay.
'assuming high opinion of' becomes 'pre' (I can't explain this - if you can you should give a lot more credence to this answer).
'own' indicates putting letters inside.
'self' becomes 'id'.
'pre' enclosing 'id' is 'PRIDE'.
Can you help me to learn more?
(Other definitions for pride that I've seen before include "''. . . . . goeth before a fall''" , "Leonine family" , "big cats" , "Hubris" , "They say it comes before a fall" .)