The most common and most likely answer to this crossword clue is the 8 letter word SPECIALS
I've seen this crossword clue in The Daily Telegraph
S
P
E
C
I
A
L
S
Buddy explains!
The straight part
We know that "Policemen" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case policemen = specials.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 SPECIALS mean?
SPECIALS noun- A reduction in consumer cost (usually for a limited time) for items or services rendered.
- One of a rotation of meals systematically offered for a lower price at a restaurant.
- Unusual or exceptional episode of a series.
- A special constable.
- Anything that is not according to normal practice, plan, or schedule, as an unscheduled run of transportation that is normally scheduled.
- Any unlicensed medicine produced or obtained for a specific individual patient.
- A correspondent; a journalist sent to the scene of an event to report back.
- A dispatch sent back by a special correspondent.
- A light that illuminates a specific person or thing on the stage.
- (nursing) To supervise a patient one-on-one.