Sick of pillagers (3)
I believe the answer is:
ill
'sick' is the definition.
('ill' can be similar in meaning to 'sick')
'of pillagers' is the wordplay.
'of' indicates a hidden word.
'ILL' can be found hidden inside 'pillagers'.
(Other definitions for ill that I've seen before include "Harm" , "Not in good health" , "Groggy" , "Badly - in need of treatment" , "Seasick" .)