Turn to celebrity for backing (5)
I believe the answer is:
pivot
'turn' is the definition.
(pivoting is a kind of turning)
'to celebrity for backing' is the wordplay.
'celebrity' becomes 'vip'.
'for backing' says the letters should be written backwards.
'to'+'vip'='tovip'
'tovip' reversed gives 'PIVOT'.
(Other definitions for pivot that I've seen before include "Central point on which things turn" , "Axis" , "Swivel" , "Central turning point" , "On which one turns" .)