An invitation to enter; no dope or corruption (4,4)

I believe the answer is:

open door

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

'an invitation to enter' is the definition.
I can't tell whether this definition defines the answer.

'no dope or corruption' is the wordplay.
'corruption' indicates an anagram.
'no'+'dope'+'or'='nodopeor'
'nodopeor' with letters rearranged gives 'OPEN-DOOR'.

Can you help me to learn more?

(Other definitions for open door that I've seen before include "Unrestricted entrance" , "Immigration policy" .)

I've seen this clue in the Sydney Morning Herald.

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