Natural to love racing off (7)
I believe the answer is:
organic
'natural to' is the definition.
(thesaurus)
'love racing off' is the wordplay.
'love' becomes 'o' (love means zero in tennis).
'off' indicates an anagram.
'racing' anagrammed gives 'rganic'.
'o'+'rganic'='ORGANIC'
(Other definitions for organic that I've seen before include "Non-chemical" , "sort of farming" , "Naturally grown" , "Made from living matter" , "Gin, Cora? (Anag)" .)