Former PM in truncated article, leader dropped by Observer (8)

I believe the answer is:

thatcher

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

'former pm' is the definition.
(I know that Thatcher was a Prime Minister of the United Kingdom)

I don't understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for thatcher that I've seen before include "who created Boris's hairstyle?" , "Former prime minister" , "Member of 7 [ORDER OF MERIT]" , "See 11" , "Former British PM" .)

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.