Policeman eating horse meat slice (4)
I believe the answer is:
Here is my best explanation:
'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'.