Bank examiner gives you this over opening investor's good books (8)
I believe the answer is:
gradient
'bank examiner' is the definition.
'gradient' can be an answer for 'bank' (thesaurus). I'm not sure about the 'examiner' bit.
'this over opening investor's good books' is the wordplay.
'this over' is an insertion indicator.
'opening' indicates taking the first letters.
'good' becomes 'grade' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'books' becomes 'nt' (New Testament).
The initial letter of 'investors' is 'i'.
'i' put into 'grade' is 'gradie'.
'gradie'+'nt'='GRADIENT'
'gives you' is the link.
Can you help me to learn more?
(Other definitions for gradient that I've seen before include "Measure of slope" , "Level of steepness" , "Inclination" , "Slope or incline" , "Bank" .)