King Cobra has no groin or vertical column? (4)

I believe the answer is:

back

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'king' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for back that I've seen before include "player in line of defence?" , "Fashionable again" , "part of the body" , "Support - rear" , "Golf holes 10-18" .)

I've seen this clue in the Irish Times (Crosaire) and The Irish Times.

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