Determined to make love in a different nest (3,2)
I believe the answer is:
set on
'determined' is the definition.
(I've seen this before)
'love in a different nest' is the wordplay.
'love' becomes 'o' (love means zero in tennis).
'in' indicates putting letters inside.
'a different' is an anagram indicator (letters placed in a different order).
'nest' with letters rearranged gives 'setn'.
'o' inserted into 'setn' is 'SET ON'.
'to make' is the link.
(Other definitions for set on that I've seen before include "Attack" , "Go" , "Determined" .)