Top lower (6)
I believe the answer is:
jersey
I believe this clue is a double definition.
'top' is the first definition.
(item of clothing)
'lower?' is the second definition.
(type of cow, something which moos or lows)
(Other definitions for jersey that I've seen before include "whose yellow variety represents the cream" , "Supplier of dairy produce" , "Breed of cattle" , "Top - cow" , "One over the moon might have been such" .)