The most common and most likely answer to this crossword clue is the 7 letter word BRAISED
I've seen this crossword clue in The Daily Telegraph
B
R
A
I
S
E
D
Buddy explains!

The straight part
We know that "cooked" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case cooked = braised.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 BRAISED mean?
BRAISED verb- To cook in a small amount of liquid, in a covered pan, somewhere between steaming and boiling.
- To join two metal pieces, without melting them, using heat and diffusion of a jointing alloy of capillary thickness.
- To burn or temper in fire.