It's important to make promise, doing so freely (4,10)

I believe the answer is:

good impression

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'it's important to' is the definition.
I can't judge whether this definition defines the answer.

'promise doing so freely' is the wordplay.
'freely' indicates anagramming the letters.
'promise'+'doing'+'so'='promisedoingso'
'promisedoingso' anagrammed gives 'GOOD IMPRESSION'.

'make' acts as a link.

Can you help me to learn more?

I've seen this clue in The Independent.

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