The most common and most likely answer to this crossword clue is the 5 plus 2 plus 4 letter word PIECE OF CAKE
I've seen this crossword clue in The Times
P
I
E
C
E
O
F
C
A
K
E
More clues leading to the result PIECE OF CAKE
Buddy explains!
The straight part
We know that "Picnic/what you might eat on it?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case picnic/what you might eat on it? = piece of cake.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.