Poem, sadly unread, about love (7)
I believe the answer is:
rondeau
'poem' is the definition.
(rondeau is a kind of poem)
'sadly unread about love' is the wordplay.
'sadly' indicates anagramming the letters.
'about' is an insertion indicator.
'love' becomes 'o' (In tennis, 'love' means 'zero').
'unread' is an anagram of 'rndeau'.
'rndeau' going around 'o' is 'RONDEAU'.
(Other definitions for rondeau that I've seen before include "form of music" , "Poem of ten or thirteen lines" , "Short lyrical poem" , "Form of poem" , "set of lines" .)