Good record label backing trendy star group (6)
I believe the answer is:
gemini
'star group' is the definition.
(I've seen this before)
'good record label backing trendy' is the wordplay.
'good' becomes 'g' (abbreviation).
'record label' becomes 'emi' (British record label).
'backing' shows that the letters should be reversed in order.
'trendy' becomes 'in' ('in' can mean fashionable).
'in' reversed gives 'ni'.
'g'+'emi'+'ni'='GEMINI'
(Other definitions for gemini that I've seen before include "lot of stars" , "May person" , "Zodiacal twins" , "star group" , "House" .)