Group of singers sing endlessly about love (5)
I believe the answer is:
choir
'group of singers' is the definition.
(a choir is a singing group)
'sing endlessly about love' is the wordplay.
'sing' becomes 'chirp' (bird song).
'endlessly' means to remove the last letter.
'about' is an insertion indicator.
'love' becomes 'o' (love means zero in tennis).
'chirp' with its last letter taken away is 'chir'.
'chir' placed around 'o' is 'CHOIR'.
(Other definitions for choir that I've seen before include "Band of singers" , "Large group of singers" , "Vocalists in group" , "People in church" , "Vocal group" .)