Behold old royal following flipping star (4)
I believe the answer is:
idol
'star' is the definition.
(idol is a kind of star)
'behold old royal following flipping' is the wordplay.
'behold' becomes 'lo' (archaic exclamation meaning 'look!').
'old royal' becomes 'Di' (Princess Diana).
'following' is a charade indicator (letters next to each other).
'flipping' says the letters should be written in reverse.
'lo'+'di'='lodi'
'lodi' in reverse letter order is 'IDOL'.
(Other definitions for idol that I've seen before include "pop star" , "Someone much loved" , "A matinee -- is a handsome actor" , "One much admired" , "Figure worshipped - sounds like someone in 7 8" .)