Repeat short, simple song on love (5)
I believe the answer is:
ditto
'repeat' is the definition.
(I know that ditto is a more specific form of the action repeat)
'short simple song on love' is the wordplay.
'short' means to remove the last letter.
'simple song' becomes 'ditty' (ditty can mean a basic song).
'on' says to put letters next to each other.
'love' becomes 'o' (love means zero in tennis).
'ditty' with its final letter taken off is 'ditt'.
'ditt'+'o'='DITTO'
(Other definitions for ditto that I've seen before include "As given above" , "As per previous" , "Same again, indicated by two dots" , "Repeat the word above" , "Two dots say same again" .)