With love, then, one’s out to win (2,3,4)
I believe the answer is:
on the nose
'win' is the definition.
(I've seen this before)
'with love then one's out' is the wordplay.
'with' indicates putting letters inside.
'love' becomes 'o' (love means zero in tennis).
'out' indicates an anagram (out can mean wrong or inaccurate).
'then'+'ones'='thenones'
'thenones' is an anagram of 'onthense'.
'o' placed into 'onthense' is 'ON THE NOSE'.
'to' is the link.
(Other definitions for on the nose that I've seen before include "Not to be placed" , "where might a boxer's punch land?" , "There's a bridge here" , "just to take the first place" , "Nasal kind of bet on horse to finish first - precisely" .)