Female cow? Buttercup, for example (6)
I believe the answer is:
flower
'buttercup for example' is the definition.
(I know that butter-flower is a type of flower)
'female cow?' is the wordplay.
'female' becomes 'f' (abbreviation).
'cow?' becomes 'lower' (an animal which moos or lows).
'f'+'lower'='FLOWER'
(Other definitions for flower that I've seen before include "One found in bed perhaps" , "Bloom" , "Blossom" , "River" , "Plant cultivated for blossoms" .)