Queen stage musical review — initially it's repetitious (9)
I believe the answer is:
iterative
'repetitious' is the definition.
('iterative' can be a synonym of 'repetitious')
'queen stage musical review initially it's' is the wordplay.
'queen' becomes 'er' (abbreviation for Elizabeth Regina).
'stage musical' becomes 'evita' (I've seen this before).
'review' shows that the letters should be reversed in order.
'initially' says to put letters next to each other.
'it's' becomes 'it' (I've seen this in other clues**).
'evita' in reverse letter order is 'ative'.
'er'+'ative'='erative'
'erative' put after 'it' is 'ITERATIVE'.
(Other definitions for iterative that I've seen before include "Involving repetition" , "repeated" , "bears repeating" , "Relating to repetition" .)