Policeman eating horse meat slice (4)
I believe the answer is:
chop
'meat slice' is the definition.
'policeman eating horse' is the wordplay.
'policeman' becomes 'cop' (I've seen this before).
'eating' indicates putting letters inside.
'horse' becomes 'h' ('H' can be a synonym of 'horse').
'cop' placed around 'h' is 'CHOP'.
(Other definitions for chop that I've seen before include "mutton slice" , "Cut into small pieces" , "Piece of meat - the sack" , "Cutlet" , "Use a cleaver" .)