A sub to replace German ones (6)

I believe the answer is:

uboats

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'german ones' is the definition.
I don't know anything about this answer so I can't judge whether this works.

'a sub to replace' is the wordplay.
'replace' indicates anagramming the letters (I've seen 'replacing' mean this (placing again)).
'a'+'sub'+'to'='asubto'
'asubto' is an anagram of 'UBOATS'.

Can you help me to learn more?

(Another definition for uboats that I've seen is " subs ...".)

I've seen this clue in The Irish Independent.

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