Cut into pieces (4)
(Other definitions for dissect that I've seen before include "Anatomize" , "Examine minutely" , "Anatomise" , "Critically examine" , "Cut open or cut apart" .)
'cut into pieces' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for chop that I've seen before include "Hew" , "Karate blow" , "Use a cleaver" , "Chinese seal" , "Thick slice of meat, often with rib" .)