Vessel about to be rebuilt (1-4)

I believe the answer is:

u-boat

'vessel' is the definition.
(U-boat is an example)

'about to be rebuilt' is the subsidiary indication.
'to be rebuilt' indicates an anagram.
'about' is an anagram of 'uboat'.

(Other definitions for u-boat that I've seen before include "German submarine of WW2" , "Take pool exercise" , "Submersible warship of WWII" , "German World War One or World War Two submarine" , "Sea vessel" .)

I've seen this clue in the Evening Standard.

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