Intend to capture marine creature not truly of the sea (6)

I believe the answer is:

merman

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'creature not truly of the sea' is the definition.
I can't judge whether this defines the answer.

'intend to capture marine' is the wordplay.
'intend' becomes 'mean' (meaning is a kind of intending).
'to capture' indicates putting letters inside.
'marine' becomes 'RM' (abbreviation for Royal Marine).
'mean' placed around 'rm' is 'MERMAN'.

Can you help me to learn more?

(Other definitions for merman that I've seen before include "Ethel --, singer" , "Half man, half fish" , "fishy character" , "Fabulous creature" .)

I've seen this clue in The Times.

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