Top beef? (6)
I believe the answer is:
jersey
This clue is a double definition.
'top' is the first definition.
(item of clothing)
'beef?' is the second definition.
(Jersey is a breed of cow)
(Other definitions for jersey that I've seen before include "tax haven?" , "Channel land < top" , "Garment - cow - island" , "Top - cow" , "Channel Island - cow" .)