Arduous journey, ultimately not for the weak (4)

I believe the answer is:

trek

'arduous journey' is the definition.
(I've seen this in another clue)

'ultimately not for the weak' is the wordplay.
'ultimately' says to take the final letters.
The last letters of 'not for the weak' are 'TREK'.

(Other definitions for trek that I've seen before include "Footslog" , "A long arduous march" , "Long and difficult trip" , "Long hard journey on foot" , "Long and difficult journey" .)

I've seen this clue in The Times.

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