The most common and most likely answer to this crossword clue is the 9 letter word STRICTEST
I've seen this crossword clue in The Daily Telegraph
S
T
R
I
C
T
E
S
T
Buddy explains!
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 STRICTEST mean?
STRICTEST adjective- Strained; drawn close; tight.
- Tense; not relaxed.
- Exact; accurate; precise; rigorously particular.
- Governed or governing by exact rules; observing exact rules; severe; rigorous.
- Rigidly interpreted; exactly limited; confined; restricted.
- Upright, or straight and narrow; — said of the shape of the plants or their flower clusters.
- Severe in discipline.
- Irreflexive; if the described object is defined to be reflexive, that condition is overridden and replaced with irreflexive.