Detective's men told to provide cover (8)
I believe the answer is:
disguise
'cover' is the definition.
(thesaurus)
'detective's men told' is the wordplay.
'detective's' becomes 'dis' (Detective Inspector).
'men' becomes 'guys'.
'told' indicates a 'sounds like' (homophone) clue.
'guys' sounds like 'guise'.
'dis'+'guise'='DISGUISE'
'to provide' is the link.
(Other definitions for disguise that I've seen before include "Clothes etc misleading as to identity" , "Misrepresent; costume" , "Camouflage, mask" , "Altered appearance" , "Cover" .)