Sub turned about (1-4)

I believe the answer is:

u-boat

'sub' is the definition.
(I know that sub can be written as U-boat)

'turned about' is the wordplay.
'turned' indicates anagramming the letters.
'about' is an anagram of 'U-BOAT'.

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

I've seen this clue in The Sun.

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