With a notorious spy novel, it's been overlooked in local enquiry? (5,4,6)
I believe the answer is:
whats your poison
'local enquiry?' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.
'with a notorious spy novel it's been overlooked in' is the wordplay.
'with' becomes 'w' (abbreviation).
'novel' indicates anagramming the letters (letters in a new or novel order).
'it's been' becomes 'ah' (I can't justify this - if you can you should give a lot more credence to this answer).
'overlooked' is a reversal indicator.
'in' means one lot of letters goes inside another.
'ah' written backwards gives 'ha'.
'notorious'+'spy'='notoriousspy'
'notoriousspy' is an anagram of 'tsyourpoison'.
'w'+'tsyourpoison'='wtsyourpoison'
'wtsyourpoison' enclosing 'ha' is 'WHATS YOUR POISON'.
Can you help me to learn more?
(Other definitions for whats your poison that I've seen before include "Local offer" , "A question that may be asked at the bar" .)