Endlessly persevering at sea, going backwards (2,7)

I believe the answer is:

in reverse

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

'endlessly persevering at sea' is the wordplay.
'endlessly' means to look at the middle letters (the ends of the words are removed).
'at sea' indicates an anagram.
The middle letters of 'persevering' are 'erseverin'.
'erseverin' anagrammed gives 'IN REVERSE'.

'going' acts as a link.
This may not be right. It may belong to another bit of the clue.

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I've seen this clue in The Independent.

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