The most common and most likely answer to this crossword clue is the 5 letter word FORCE
I've seen this crossword clue in Independent
F
O
R
C
E
More clues leading to the result FORCE
- Not against an Established Church's power
- Stuff from police agent in US containing drug
- Police perhaps paid to break hunger strike?
- Group assembled for collective action in favour of church
- Influence in favour of church
- Agency supporting the established church
- Wanting to have church police
- see 2dn.
- Clad in iron, a baddie for Tolkien’s army
- In favour of church power
Buddy explains!

The straight part
We know that "police" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case police = force.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 FORCE mean?
FORCE noun- Strength or energy of body or mind; active power; vigour; might; capacity of exercising an influence or producing an effect.
- Power exerted against will or consent; compulsory power; violence; coercion.
- Anything that is able to make a substantial change in a person or thing.
- A physical quantity that denotes ability to push, pull, twist or accelerate a body and which has a direction and is measured in a unit dimensioned in mass × distance/time² (ML/T²): SI: newton (N); CGS: dyne (dyn)
- Something or anything that has the power to produce a physical effect upon something else, such as causing it to move or change shape.
- A group that aims to attack, control, or constrain.
- The ability to attack, control, or constrain.
- A magic trick in which the outcome is known to the magician beforehand, especially one involving the apparent free choice of a card by another person.
- Legal validity.
- Either unlawful violence, as in a "forced entry", or lawful compulsion.
- Ability of an utterance or its element (word, form, prosody, ...) to effect a given meaning.
- (with the, often capitalized) A metaphysical and ubiquitous power from the fictional Star Wars universe created by George Lucas. See usage note.
- To violate (a woman); to rape.
- To exert oneself, to do one's utmost.
- To compel (someone or something) to do something.
- To constrain by force; to overcome the limitations or resistance of.
- To drive (something) by force, to propel (generally + prepositional phrase or adverb).
- To cause to occur (despite inertia, resistance etc.); to produce through force.
- To forcibly open (a door, lock etc.).
- To obtain or win by strength; to take by violence or struggle; specifically, to capture by assault; to storm, as a fortress.
- To create an out by touching a base in advance of a runner who has no base to return to while in possession of a ball which has already touched the ground.
- (whist) To compel (an adversary or partner) to trump a trick by leading a suit that he/she does not hold.
- To put in force; to cause to be executed; to make binding; to enforce.
- To provide with forces; to reinforce; to strengthen by soldiers; to man; to garrison.
- To allow the force of; to value; to care for.
- (law enforcement) Any police organization; a constabulary.
- A waterfall or cascade.
- To stuff; to lard; to farce.