Detective reading for fun (9)
I believe the answer is:
diversion
'fun' is the definition.
(thesaurus)
'detective reading' is the wordplay.
'detective' becomes 'di' (Detective Inspector abbreviation).
'reading' becomes 'version' (a reading can be an interpretation or version).
'di'+'version'='DIVERSION'
'for' acts as a link.
(Other definitions for diversion that I've seen before include "Detour" , "Alternative route" , "entertainment" , "Amusement -- temporary redirection" .)