Ex marine thrashed inspector (8)

I believe the answer is:

examiner

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

'inspector' is the definition.
(I know that inspector can be written as examiner)

'ex marine thrashed' is the wordplay.
'ex marine' anagrams to 'EXAMINER'.
Though, I'm not clear how this is indicated.

Can you help me to learn more?

(Other definitions for examiner that I've seen before include "Tester or inspector" , "Meaner XI (anag)" , "Test setter" , "One administering test" , "Newspaper" .)

I've seen this clue in The Sun.

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.