Fast U-boat bags slow ship (3)

I believe the answer is:

tub

'slow ship' is the definition.

'fast u-boat bags' is the wordplay.
'bags' says the answer is hidden in the clue.
'TUB' is hidden in the letters of 'fast u boat'.

(Other definitions for tub that I've seen before include "'Broad, open vessel (3)'" , "Maybe it sailed" , "Wide container; boat" , "Pot (of e.g. ice-cream)" , "Bath; leaky ship" .)

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

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