The most common and most likely answer to this crossword clue is the 5 plus 4 letter word SPEED TRAP
I've seen this crossword clue in The Guardian
S
P
E
E
D
T
R
A
P
More clues leading to the result SPEED TRAP
- Regions across sea to the west, a hazard for travellers in haste?
- Police control hard to understand in areas to the west
- Pad, pre-set, tripped where boy racer nabbed?
- Device used by police ending in convictions — not entirely shallow then, on reflection?
- Jaguars might be caught in this
- Police equipment motormouth’s split up
- Secured by belt, reversing down — motorist slower?
- Drivers aren’t slow to fall into it
- Where police may have stopped car, a driver finally stepped out
Buddy explains!
The straight part
We know that "Device used by police" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case device used by police = speed trap.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.