... must have made joint attack to depose king (4)

I believe the answer is:

need

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

'must have' is the definition.
(I've seen this in another clue)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for need that I've seen before include "destitute state" , "Lack - demand" , "Rely on" , "state requiring relief" , "Require (as essential)" .)

I've seen this clue in The Independent.

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.