Sing sloppy corn about love? (5)
I believe the answer is:
croon
'sing' is the definition.
(I know that croon is a more specific form of the action sing)
'sloppy corn about love?' is the wordplay.
'sloppy' indicates anagramming the letters.
'about' indicates putting letters inside.
'love?' becomes 'o' (love means zero in tennis).
'corn' is an anagram of 'cron'.
'cron' placed around 'o' is 'CROON'.
(Other definitions for croon that I've seen before include "Sing with a soft voice" , "Sing like Bing" , "Sing softly" , "Sing in a soft low tone" .)