Foxes skinned by northern cattle (4)
I believe the answer is:
oxen
'cattle' is the definition.
(type of cattle)
'foxes skinned by northern' is the wordplay.
'skinned' means to look at the middle letters.
'by' says to put letters next to each other.
'northern' becomes 'n' (abbreviation e.g. N. Ireland).
The central letters of 'foxes' are 'oxe'.
'oxe'+'n'='OXEN'
(Other definitions for oxen that I've seen before include "Beef stock" , "Bovine mammals" , "Domesticated bovines" , "Domesticated bovine draft animals" , "Cows and bulls" .)