Working back with Spooner? No good for nobody! (3-6)
I believe the answer is:
non-person
'for nobody' is the definition.
(I've seen this before)
'working back with spooner? no good' is the wordplay.
'working back' becomes 'nn' (I can't explain this - if you can you should give a lot more credence to this answer).
'with' is an insertion indicator.
'no good' is an anagram indicator (no good can mean faulty or defective).
'spooner' with letters rearranged gives 'onperso'.
'nn' enclosing 'onperso' is 'NON-PERSON'.
Can you help me to learn more?
(Other definitions for non-person that I've seen before include "Way out" , "Celebrity now in obscurity" .)