Counter everything during my arrest (6)
I believe the answer is:
collar
'arrest' is the definition.
(I know that arrest can be written as collar)
'counter everything during my' is the wordplay.
'counter' is a reversal indicator (counter can mean in the opposite direction).
'everything' becomes 'all' (all things).
'during' indicates putting letters inside.
'my' becomes 'cor' (both are expressions of surprise).
'all' backwards is 'lla'.
'lla' going within 'cor' is 'COLLAR'.
(Other definitions for collar that I've seen before include "Arrest - part of garment" , "Nick" , "Band around garment's neck" , "Be hot under the . . . . . . to be angry or resentful" , "Item worn around the neck" .)