Pester chaps involved in civil wrong (7)
I believe the answer is:
torment
'pester' is the definition.
(I've seen this before)
'chaps involved in civil wrong' is the wordplay.
'chaps' becomes 'men' (chap means a man).
'involved in' indicates putting letters inside.
'civil wrong' becomes 'tort' (synonyms).
'men' inserted inside 'tort' is 'TORMENT'.
(Other definitions for torment that I've seen before include "Severe pain" , "Harry" , "Torture" , "Agony of mind" , "Hound" .)