Crossword Genius

Gone case? (6)

Ross

I believe the answer is:

coffin

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

'case?' is the definition.
(thesaurus)

'gone' is the wordplay.
I cannot quite understand how this works, but
'gone' could be 'off' (I've seen this before) and 'off' is present in the answer.
This explanation may well be incorrect...

Can you help me to learn more?

(Other definitions for coffin that I've seen before include "Box for a corpse" , "Body box" , "Casket for the dead" , "Casket for a corpse" , "Corpse's chest" .)

I've seen this clue in The Hindu.
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