Adviser employed by raiders (4)
I believe the answer is:
aide
'adviser' is the definition.
'employed by raiders' is the wordplay.
'employed by' indicates a hidden word.
'AIDE' is hidden in the letters of 'raiders'.
(Other definitions for aide that I've seen before include "Officer who acts as military assistant" , "auxiliary" , "Right-hand man/woman" , "Second" , "Confidential assistant or advisor" .)