Inflexible tail (5)

I believe the answer is:

stern

I believe this clue is a double definition.

'inflexible' is the first definition.
(similar in meaning)

'tail' is the second definition.
(back of a ship or boat)

(Other definitions for stern that I've seen before include "Grim, strict" , "Demanding < back" , "Back end of a ship" , "Unrelenting at the back of the boat?" , "Where sailors may be" .)

I've seen this clue in The Guardian.

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