A duck or ducks (4)
I believe the answer is:
love
This clue is a double definition.
'a duck' is the first definition.
(duck and love can mean zero in sports)
'ducks' is the second definition.
(both are terms of endearment)
'or' is the link.
(Other definitions for love that I've seen before include "Zero score, dear" , "Passionate desire" , "Disappointing score" , "affair? On the contrary" , "Score of zero at tennis" .)