Words used in making an arrest (4,2)
I believe the answer is:
stop it
'words used in' is the definition.
I know nothing about this answer so I cannot tell whether this works.
'an arrest' is the wordplay.
I cannot quite see how this works, but
'an' could be 'i' (Roman numeral for one) and 'i' is located in the answer.
'arrest' could be 'stop' (synonyms) and 'stop' is located in the answer.
A single letter 't' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
'making' is the link.
Can you help me to learn more?
(Other definitions for stop it that I've seen before include "Desist!" , "Don't" .)