The most common and most likely answer to this crossword clue is the 6 letter word RECIPE
I've seen this crossword clue in The Times
R
E
C
I
P
E
More clues leading to the result RECIPE
- Instructions read initially, before piece cooked
- Ready to assimilate City formula
- Instructions on what's regularly used by chippies
- Set of instructions to get new piece fitted to back of door
- Plan in relation to Channel Islands gym
- Great queen backing formula
- Formula ready for use city area gets brought in
- Concerned with cold and broken pie dish
- In retreat, heroic national leader's instructions
- Instructions for course in leisure centre, one with gym
Buddy explains!

The straight part
We know that "formula" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case formula = recipe.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 RECIPE mean?
RECIPE noun- A formula for preparing or using a medicine; a prescription; also, a medicine prepared from such instructions.
- Any set of instructions for preparing a mixture of ingredients.
- By extension, a plan or procedure to obtain a given end result; a prescription.
- Now especially, a set of instructions for making or preparing food dishes.
- A set of conditions and parameters of an industrial process to obtain a given result.