Cutting comment on royal stylist (6)
I believe the answer is:
barber
'stylist' is the definition.
(barber is a kind of stylist)
'cutting comment on royal' is the wordplay.
'cutting comment' becomes 'barb' (I've seen this in another clue).
'on' is a charade indicator (letters next to each other).
'royal' becomes 'er' (abbreviation for Elizabeth Regina).
'barb'+'er'='BARBER'
(Other definitions for barber that I've seen before include "A gent's haircutter" , "Hair cutter" , "American composer; hairdresser" , "One who cuts hair" , "Man's hairdresser - from Seville?" .)