Cow's bottom? (5)
I believe the answer is:
lower
I believe this clue is a double definition.
'cow's' is the first definition.
(I've seen this in other clues)
'bottom?' is the second definition.
('lower' can be similar in meaning to 'bottom')
(Other definitions for lower that I've seen before include "disgrace" , "put down" , "where are trousers in relation?" , "Take down" , "Bring down" .)