Whole "Triangle" at sea (8)

I believe the answer is:

integral

'whole' is the definition.
(similar in meaning)

'triangle at sea' is the wordplay.
'at sea' indicates anagramming the letters.
'triangle' anagrammed gives 'INTEGRAL'.

(Other definitions for integral that I've seen before include "'Inherent, inbuilt (8)'" , "Forming part of the whole" , "Full" , "A component and indispensable part of, like triangle" , "Maths function; entire" .)

I've seen this clue in The Telegraph.

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