Keep straying from one's post (4)

I believe the answer is:

stop

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'keep' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Perhaps you can see a link between them that I don't see?

'straying from one's post' is the wordplay.
'post' anagrams to 'STOP'.
However, I am unsure how the anagram is indicated.

Can you help me to learn more?

(Other definitions for stop that I've seen before include "Cease, halt" , "Halt, whoa, desist" , "Knock out" , "Check" , "Cease, desist, whoa" .)

I've seen this clue in the Evening Standard.

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