Go into US headquarters avoiding cold (5)

I believe the answer is:

enter

I'm a little stuck... Click here to teach me more about this clue!

'go into' is the definition.
(enter can mean to go into a place)

I don't understand the rest of the clue.

(Other definitions for enter that I've seen before include "Get in" , "submit?" , "put in for a race" , "Enrol" , "Enlist, join up" .)

I've seen this clue in The Guardian.

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