Leading economist briefly goes over books (7)
I believe the answer is:
keynote
'leading economist' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'briefly goes over books' is the wordplay.
'briefly' becomes 'k'.
'goes' becomes 'eyne' (I can't justify this - if you can you should believe this answer much more).
'over' means one lot of letters goes inside another.
'books' becomes 'OT' (Old Testament).
'eyne' enclosing 'ot' is 'eynote'.
'k'+'eynote'='KEYNOTE'
Can you help me to learn more?
(Other definitions for keynote that I've seen before include "The central speech of a conference" , "Gist" , "Determining principle in a speech" , "Principal theme (eg of a speech)" , "of fundamental importance" .)