Detective's men reportedly providing cover (8)
I believe the answer is:
disguise
'cover' is the definition.
(I've seen this before)
'detective's men reportedly' is the wordplay.
'detective's' becomes 'di's' (Detective Inspector abbreviation).
'men' becomes 'guys' (I've seen this in another clue).
'reportedly' shows a homophone (sound like).
'guys' sounds like 'guise'.
'dis'+'guise'='DISGUISE'
'providing' acts as a link.
(Other definitions for disguise that I've seen before include "Change of appearance for concealment" , "Camouflage to hide identity" , "Alter appearance to conceal identity" , "Pretence" , "Clothes etc misleading as to identity" .)