Group of musicians love star, Cher, performing (9)
I believe the answer is:
orchestra
'group of musicians' is the definition.
(I've seen this before)
'love star cher performing' is the wordplay.
'love' becomes 'o' (love means zero in tennis).
'performing' indicates an anagram (the letters move around or 'perform').
'star'+'cher'='starcher'
'starcher' with letters rearranged gives 'rchestra'.
'o'+'rchestra'='ORCHESTRA'
(Other definitions for orchestra that I've seen before include "A number of musicians" , "Ensemble of players" , "Gamelan, for instance" , "Large body of musicians" , "Large group of players" .)