Opera star being tricky — one creates divisions (9)
I believe the answer is:
separator
'one creates divisions' is the definition.
(someone who separates or divides things)
'opera star being tricky' is the wordplay.
'being tricky' indicates anagramming the letters.
'opera'+'star'='operastar'
'operastar' with letters rearranged gives 'SEPARATOR'.
(Other definitions for separator that I've seen before include "Opera star (anag.)" , "What keeps things apart" .)