Police engaging a head? Some scoff! (4,4)
I believe the answer is:
meat loaf
'some scoff' is the definition.
('scoff' can mean food)
'police engaging a head?' is the wordplay.
'police' becomes 'met' (London Metropolitan Police).
'engaging' indicates putting letters inside.
'head?' becomes 'loaf' (slang term for the head).
'met' going around 'a' is 'meat'.
'meat'+'loaf'='MEAT-LOAF'
(Other definitions for meat loaf that I've seen before include "Bully-beef etc" , "hot dish" , "Minced beef dish" , "baked in a tin?" , "To a flame (anag.)" .)