Apt to churn a little butter (3)
I believe the answer is:
pat
'a little butter' is the definition.
('pat' can mean a lump of butter)
'apt to churn' is the wordplay.
'to churn' indicates an anagram (I've seen 'churning' mean this).
'apt' with letters rearranged gives 'PAT'.
(Other definitions for pat that I've seen before include "Tap lightly" , "Light hand stroke" , "Touch lightly - bit of butter?" , "Small butter piece" , "Touch; name" .)