Crossword Genius

Letters from author not glad to have stopped (6,2,1,4)

Ross

I believe the answer is:

ground to a halt

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

'stopped' is the definition.
(I've seen this before)

'letters from author not glad to have' is the wordplay.
'author not glad' anagrams to 'GROUND TO A HALT'.
But, I'm not sure how this is indicated.

Can you help me to learn more?

(Other definitions for ground to a halt that I've seen before include "stuck" , "Slowed down gradually and then stopped" .)

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