The most common and most likely answer to this crossword clue is the 13 letter word MASSACHUSETTS
I've seen this crossword clue in Independent
M
A
S
S
A
C
H
U
S
E
T
T
S
More clues leading to the result MASSACHUSETTS
- State schools must chase SATs
- Lots of people and children in US state, possibly this one?
- The full version of Mass
- State hates cuts planned in service
- State must act as she’s in a mess
- State ceremony by church held amongst sculpted statues
- US state littered with chasms – not this one
- In a state, cats set off with Shamus
Buddy explains!

The straight part
We know that "‘this one’ (US state)" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case ‘this one’ (us state) = massachusetts.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.