Space formed by police where things are at boiling point? (6)

I believe the answer is:

kettle

I'm a little stuck... Click here to teach me more about this clue!

'boiling point?' is the definition.
(I've seen this in another clue)

I don't understand the remainder of the clue.

(Other definitions for kettle that I've seen before include "Contain demonstrators" , "Water boiler" , "Kitchen water heater" , "One called black by pot" , "Check elements causing trouble in demonstration" .)

I've seen this clue in The Times.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.