Knight's speech on crowbarring was astonishing (10)
I believe the answer is:
surprising
'astonishing' is the definition.
(similar in meaning)
'knight's speech on crowbarring was' is the wordplay.
I cannot really see how this works, but
'was' could be 'is' (being is a kind of being) and 'is' is found in the answer.
'knight' could be 'n' (chess abbreviation) and 'n' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for surprising that I've seen before include "Mildly astonishing" , "Causing astonishment" , "Unexpected" .)