The one time to regret nothing (4,4)

I believe the answer is:

true love

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'the one' is the definition.
I don't know anything about this answer so I can't judge whether this works.

'time to regret nothing' is the wordplay.
'time' becomes 't' (abbreviation).
'to regret' becomes 'rue' (to rue something is to regret it).
'nothing' becomes 'love' (love means zero in tennis).
't'+'rue'+'love'='TRUE-LOVE'

Can you help me to learn more?

(Another definition for true love that I've seen is " Genuine affection?".)

I've seen this clue in The Independent.

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