Time after time, love is a source of inspiration (5)
I believe the answer is:
erato
'a source of inspiration' is the definition.
(one of the muses in Greek myth)
'time after time love' is the wordplay.
'time' becomes 'era' (era is a kind of time).
'after' says to put letters next to each other.
'time' becomes 't' (abbreviation).
'love' becomes 'o' (love means zero in tennis).
'era'+'t'+'o'='ERATO'
'is' is the link.
(Other definitions for erato that I've seen before include "Arts patron" , "Muse of 11 and 23" , "Source of artistic inspiration" , "Muse of lyric love-poetry" , "inspiration for poetry" .)