Turn sanctimonious over casino game after losing pounds (9)
I believe the answer is:
pirouette
'turn' is the definition.
(I've seen this before)
'sanctimonious over casino game after losing pounds' is the wordplay.
'sanctimonious' becomes 'pi'.
'over' says to put letters next to each other.
'casino game' becomes 'roulette' (I've seen this before).
'after losing' indicates named letters should be taken away.
'pounds' becomes 'l' (L can represent the monetary pound).
'roulette' with 'l' taken out is 'rouette'.
'pi'+'rouette'='PIROUETTE'
(Other definitions for pirouette that I've seen before include "Balletic whirl" , "Take turn on foot" , "Dancer's twirl" , "Rapid spin of the body on the toes in ballet" , "Tore up tie (anag) - spin" .)