The most common and most likely answer to this crossword clue is the 10 letter word INGREDIENT
I've seen this crossword clue in The Daily Telegraph
I
N
G
R
E
D
I
E
N
T
More clues leading to the result INGREDIENT
- Component French artist briefly noted initially in food allowance
- I get dinner prepared, using this?
- . Constituent of Rayner ultimately needing it sorted out
- Drinking red I entertained, taking part
- At home with fellow drinking wine, I will offer something in the kitchen?
- Green tin I’d stirred, food added
- Constituent blasted dingier hospital department
- Cook determining, having lost heart, what to put in food
- Contents of green tin I’d poured out as part of recipe
- Going red I entertained, accepting part
Buddy explains!

The straight part
We know that "what to put in food" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case what to put in food = ingredient.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 INGREDIENT mean?
INGREDIENT noun- One of the substances present in a mixture, especially food.