The most common and most likely answer to this crossword clue is the 10 letter word CAPITALISE
I've seen this crossword clue in Financial Times
C
A
P
I
T
A
L
I
S
E
Buddy explains!
The straight part
We know that "put in a different case" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case put in a different case = capitalise.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 CAPITALISE mean?
CAPITALISE verb- In writing or editing, to write (something: either an entire word or text, or just the initial letter(s) thereof) in capital letters, in upper case.
- To contribute or acquire capital (money or other resources) for.
- To convert into capital, i.e., to get cash or similar immediately fungible resources for some less fungible property or source of future income.
- To treat as capital, not as an expense.
- To profit or to obtain an advantage.
- (followed by on) To seize, as an opportunity; to obtain a benefit; to invest on something profitable.