The most common and most likely answer to this crossword clue is the 16 letter word BEST-BEFORE-DATE
B
E
S
T
-
B
E
F
O
R
E
-
D
A
T
E
Buddy explains!
The straight part
We know that "timing advice for chef?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case timing advice for chef? = best-before-date.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.