The meaning of love (4)

I believe the answer is:

zero

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'love' is the definition.
(love is zero in tennis)

I don't understand the remainder of the clue.

(Other definitions for zero that I've seen before include "See 22" , "Less than one" , "The hour to leave" , "[NIX]" , "Nada" .)

I've seen this clue in the Evening Standard.

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