The most common and most likely answer to this crossword clue is the 4 letter word CURD
I've seen this crossword clue in The Daily Telegraph
C
U
R
D
Buddy explains!

The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does CURD mean?
CURD noun- The part of milk that coagulates when it sours or is treated with enzymes; used to make cottage cheese, dahi, etc.
- The coagulated part of any liquid.
- The edible flower head of certain brassicaceous plants.
- To form curd; to curdle.
- To cause to coagulate or thicken; to cause to congeal; to curdle.