Sewing is irritation during police operation (9)
I believe the answer is:
stitching
'sewing' is the definition.
('stitch' can be a synonym of 'sew')
'irritation during police operation' is the wordplay.
'irritation' becomes 'itch' (an itch irritates you).
'during' indicates putting letters inside.
'police operation' becomes 'sting' (sting can mean a police operation).
'itch' put into 'sting' is 'STITCHING'.
'is' acts as a link.
(Other definitions for stitching that I've seen before include "Perhaps is repairing" , "Using needle and thread" , "Fasten by sewing" , "Sutures" , "achieving closure of wound" .)