The most common and most likely answer to this crossword clue is the 11 plus 3 letter word UNSATURATED FAT
U
N
S
A
T
U
R
A
T
E
D
F
A
T
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.