Your setter would appeal arrests over dope (5)
I believe the answer is:
idiot
'dope' is the definition.
(I've seen this before)
'your setter would appeal arrests over' is the wordplay.
'your setter would' becomes 'I'd' ('I would' - referring to the crossword setter).
'appeal' becomes 'it' ('it' can mean something attractive or appealing).
'arrests' indicates putting letters inside (inserted letters are contained or arrested).
'over' becomes 'o' (cricket abbreviation).
'it' enclosing 'o' is 'iot'.
'id'+'iot'='IDIOT'
(Other definitions for idiot that I've seen before include "Sap" , "Ass, ninny" , "Stupid person" , "nutter" , "Dolt" .)