Mammoth in doomed vessel (7)

I believe the answer is:

titanic

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

This clue could be a double definition.

'mammoth' is the first definition.
(I've seen this in another clue)

'doomed vessel' is the second definition.
'titanic' can be an answer for 'vessel' (I've seen this before). I am unsure of the 'doomed' bit.

'in' is the link.

Can you help me to learn more?

(Other definitions for titanic that I've seen before include "Of exceptional strength or size" , "Huge - disaster struck this ship" , "made of metal" , "Huge, epic" , "Famously sunken ship" .)

I've seen this clue in The Telegraph and The Sun.

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