Hard-working policeman's fired, having concealed information (8)
I believe the answer is:
diligent
'hard-working' is the definition.
(thesaurus)
'policeman's fired having concealed information' is the wordplay.
'policeman' becomes 'di' (I've seen this in other clues**).
'fired' becomes 'lit' (set on fire).
'having concealed' indicates putting letters inside.
'information' becomes 'gen' (gen is a kind of information).
'lit' enclosing 'gen' is 'ligent'.
'di'+'ligent'='DILIGENT'
(Other definitions for diligent that I've seen before include "Painstaking - I tingled (anag)" , "Steady in application and industry" , "I tingled, being hard-working and meticulous" , "Showing care and effort" , "Taking trouble" .)