Excited Americans get all this! (3,2)

I believe the answer is:

het up

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'excited' is the definition.
(synonyms)

I don't understand how the remainder of the clue works.

(Other definitions for het up that I've seen before include "Upset, agitated" , "in a rage?" , "Irate" , "Angry - agitated" , "On edge - agitated" .)

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