Spy, note, probing a lot of evidence of murder? (4)
I believe the answer is:
bond
'spy' is the definition.
(James Bond)
'note probing a lot of evidence of murder?' is the wordplay.
'note' becomes 'n' (abbreviation).
'probing' is an insertion indicator (probe can mean to make a hole in).
'a lot of evidence of murder?' becomes 'bod' (I can't justify this - if you can you should believe this answer much more).
'n' put inside 'bod' is 'BOND'.
Can you help me to learn more?
(Other definitions for bond that I've seen before include "Binding agreement; double zero seven" , "Tie - debenture" , "Fastening; financial certificate" , "secure?" , "one licensed to kill" .)