Shows displeasure when put out (5)

I believe the answer is:

sulks

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'shows' is the definition.
Although both the answer and definition are verbs in their -s form, I don't see how one could define the other.

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for sulks that I've seen before include "Shows petty resentment" , "Pet" , "Fit of pique" , "Is sullen and ill-tempered" , "Broods" .)

I've seen this clue in the Evening Standard.

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