Endless amusement with setter setting (9)
I believe the answer is:
placement
'setting' is the definition.
(thesaurus)
'endless amusement with setter' is the wordplay.
'endless amusement' becomes 'pla' (I can't explain this - if you can you should believe this answer much more).
'with' means one lot of letters go next to another.
'setter' becomes 'cement' (something that sets).
'pla'+'cement'='PLACEMENT'
Can you help me to learn more?
(Other definitions for placement that I've seen before include "Temporary posting" , "location" , "period of work experience" , "Temporary job for work experience" , "Arrangement" .)