When single love is at first divine (3)
I believe the answer is:
odd
'when single' is the definition.
'odd' can be an answer for 'single' (thesaurus). I am not certain of the 'when' bit.
'love is at first divine' is the wordplay.
'love' becomes 'o' (love means zero in tennis).
'is at first' means one lot of letters go next to another.
'divine' becomes 'dd' (divine can mean theologian eg Doctor of Divinity).
'o'+'dd'='ODD'
Can you help me to learn more?
(Other definitions for odd that I've seen before include "Peculiar sort of number?" , "Extraordinary" , "Abnormal" , "Funny" , "Queer" .)