Turn, facing celebrity's back (5)
I believe the answer is:
pivot
'turn' is the definition.
(pivoting is a kind of turning)
'facing celebrity's back' is the wordplay.
'facing' becomes 'to' (facing can mean pointed to or towards).
'celebrity' becomes 'vip' (Very Important Person).
'back' is a reversal indicator.
'to'+'vip'='tovip'
'tovip' written backwards gives 'PIVOT'.
(Other definitions for pivot that I've seen before include "Kind of wine grape" , "Pin, centre of revolution" , "Point about which something turns" , "On which one turns" , "Turning pin" .)