The most common and most likely answer to this crossword clue is the 3 plus 5 letter word RED LIGHT
I've seen this crossword clue in The Daily Telegraph
R
E
D
L
I
G
H
T
More clues leading to the result RED LIGHT
- Warning sign on entrance: “No English!”
- Warning sign on entrance: “No English here”
- Sign of danger: Tory embracing Balls and Labour leader
- . Socialist view of brothels
- Warning sign of Tory describing far-right group
- Sign to stop on date with blonde?
- Seedy district where waiting is a must
- Stop replacing work with wild orgies, bristling
- 27 It’s best not to shoot one in colour before daybreak
- What tells you to stop getting led astray — with proper protection
Buddy explains!
The straight part
We know that "What tells you to stop" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case what tells you to stop = red light.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.