What is former approach?
That would depend on how it was used,
It could mean the method or way of doing things that was used in the past but is not used now.
It could also be used as a way of referring to the first of two approaches just mentioned.
If you tell us more about where you saw the phrase we can give you a more specific answer.
previous method/attitude

If you want more precise information, you will have to give us your sentence.

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