Reveal advice on how to be less reserved? (4,2)

I believe the answer is:

open up

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'reveal' is the definition.
(thesaurus)

I can't explain the remainder of the clue.

(Other definitions for open up that I've seen before include "Begin firing; disclose" , "Unlock building or reveal inner thoughts" , "Talk more freely" , "become less cloistered" , "Begin shooting; become more confiding" .)

I've seen this clue in The Globe and Mail, The Telegraph and The Guardian.

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