Invitation to gratification in seedy São Paulo resort (2,2,3,6)

I think it could be either:

go as you please

do as you please

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

'invitation to gratification' is the definition.

'seedy sao paulo resort' is the wordplay.
I cannot really see how this works, but
an anagram of 'sao' is 'oas' which is located in the answer.
This may be the basis of clue (or it may be nonsense).

'in' acts as a link.

Can you help me to learn more?

I've seen this clue in The Everyman puzzle in The Observer.

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