Sick of pillaging (3)
I believe the answer is:
ill
'sick' is the definition.
(I know that sick can be written as ill)
'of pillaging' is the wordplay.
'of' says the answer is hidden in the clue.
'ILL' can be found hidden inside 'pillaging'.
(Other definitions for ill that I've seen before include "Evil or sick" , "Off colour?" , "Ailing" , "poor" , "US state" .)