Not keen for seconds of walnut dip? (4)
I believe the answer is:
anti
'not' is the definition.
(I've seen this in other clues)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for anti that I've seen before include "Against, informally" , "(Person who is) not in favour" , "Prefix meaning against" , "[NO MAN]" , "Opposed to followers of Hitler" .)