The perfect words to describe a really good relationship (4,2,5)

I think it could be either:

Which length description are you looking for?:

4,2,5

11*

best of terms

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'the perfect words to describe a really' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.

'good relationship' is the wordplay.
I cannot really see how this works, but
'good' could be 'best' (similar in meaning) and 'best' is found within the answer.
'relationship' could be 'terms' (eg terms of a business relationship) and 'terms' is found in the answer.
The remaining letters 'of' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...

Can you help me to learn more?

I've seen this clue in the Evening Standard.

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