My tough love has inspired hatred primarily on the climb (2,3)
I believe the answer is:
oh boy
'my' is the definition.
(both are expressions of surprise)
'tough love has inspired hatred primarily on the climb' is the wordplay.
'tough' becomes 'yob' (both can mean a violent person).
'love' becomes 'o' (love means zero in tennis).
'has inspired' indicates putting letters inside (inserted letters are breathed in or \'inspired\').
'primarily' says to take the initial letters.
'on the climb' says the letters should be written backwards (in a down clue, letters climb up).
The initial letter of 'hatred' is 'h'.
'yob'+'o'='yobo'
'yobo' enclosing 'h' is 'yobho'.
'yobho' written backwards gives 'OH BOY!'.
(Other definitions for oh boy that I've seen before include "Expression of enthusiasm, pleasure, etc" , "Blimey!" .)