The most common and most likely answer to this crossword clue is the 9 letter word PATERNITY
I've seen this crossword clue in The Guardian
P
A
T
E
R
N
I
T
Y
More clues leading to the result PATERNITY
Buddy explains!

The straight part
We know that "Such a suit" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case such a suit = paternity.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 PATERNITY mean?
PATERNITY noun- Fatherhood, being a father
- Parental descent from a father
- Legal acknowledgement of a man's fatherhood of a child
- Authorship