Butcher and hack get a move on! (4,4)
I believe the answer is:
chop chop
'get a move on' is the definition.
(phrase used to tell someone to hurry up)
'butcher and hack' is the wordplay.
'butcher' becomes 'chop' (I can't justify this - if you can you should give a lot more credence to this answer).
'and' says to put letters next to each other.
'hack' becomes 'chop' (synonyms).
'chop'+'chop'='CHOP-CHOP'
Can you help me to learn more?
(Other definitions for chop chop that I've seen before include "Quickly!" , "with expedition" , "Promptly!" , "Get a move on" , "Repeatedly use machete" .)