Erects constructively under cover (6)

I believe the answer is:

secret

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

'under cover' is the definition.
(thesaurus)

'erects constructively' is the wordplay.
'erects' can be anagrammed to 'SECRET'.
Though, I'm unsure how the anagram is indicated.

Can you help me to learn more?

(Other definitions for secret that I've seen before include "away from scrutiny" , "Not seen or know by others" , "Not known by others" , "Cloak-and-dagger" , "Private, covert" .)

I've seen this clue in the Evening Standard.

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